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Wednesday, April 25, 2018

MATHS

X Standard

ARITHMETIC SEQUENCES



1.  a) Write a sequence by adding 3 with the multiples of 7. 

     b) Write its algebraic  form
   

  c)  Is 2000 a term of this sequence ?

2. . The common difference of two arithmetic sequence are equal.  
     The difference  between their  first terms are 10.  
     a) What is the difference between the second  terms ?  
     b) What is the difference between the nth terms?,   
     c) What is the difference between the sums of first n terms ?
3. The sum of first n terms of an arithmetic sequence is 3n2 + 4n
   a) What is its first term ?   b) Write the algebraic form of the sequence.       c) Find the 20th term.
4.  Is 44 a term of the sequence 4n + 3 ? Why ?  Can the difference 
    between any 2 term be  44?
5  . In the arithmetic sequence 6,10,14,.......        a) How much more is
     the 15th term  than the 10th term ?   
    b) Which term is 32 more than the 20th term ?
6. The common difference of an arithmetic sequence is 6 and its 9th
     term is zero.   a) Write the first term  and 17th term.       
     b) Find the sum of its first 17 terms.
7. 16th term of an arithmetic sequence is 60 and its 26th term is 90.
     a) What is the difference between the 16th term and 26th term ?      
     b) What is the  common difference?    c) Write the sequence
8.  a, Write the half of  natural numbers as a sequence.       
     b) Write the integers  in  that sequence in order.   
     c) What will be the position of the number 23 in the  first sequence ? . 
     d) Find the sum of the first fifty terms of the first sequence.
9. The algebraic expression of an arithmetic sequence is 8n+11
    a) Write the common difference of the sequence.         
    b) What is the remainder  got when each term of this  sequence is 
        divided by the common  difference?.    
     c) Is 11 a term of this sequence? Why?
10. In the Arithmetic sequence   ½ , 4/3, 13/6,  .......    a) What is the 
      common  difference?   b) Which is the first integer term in the 
     sequence?          

  11. Fifth term of an arithmetic sequence is   18.  Find the sum of scond  
        term and  eight  term ?  If the common difference is 3 find the first     
        term ?
12. The algebraic expression of an arithmetic sequence is 6n+1
    a) Write the sequence?.     b) What is the remainder when the terms are
       divided by 6?    c) Write the algebraic expression of the sequence obtained
       by the natural numbers which leaves a remainder 2   on division by 6?
13. The sum of first 15 terms of an arithmetic sequence is 300.
       a) What is its 8th term?.       b)If the first term is 6 find its common
        difference?      c) Write the algebraic expression of this sequence?
14. The algebraic expression of an arithmetic sequence is 5n-3.
     a) Find the  first  term?.       b)  Find the sum of first 39 terms ?
15. The sum of first 5 terms of an arithmetic sequence is 60. Write the
     sequence?
16.a). Write the arithmetic sequence with first term 1 and common difference
        ½?    b)  Find its 31st term?.       c) Calculate the sum of its first 31 terms?
17. a), The 10th term of an Arithmetic sequence is 20 and 20th term is 10
      b) What is its common difference?.       c) Find its 30th term?
18.  a).What is the common difference of the arithmetic sequence 80,76,72,.......
      b). How many positive numbers are there in this sequence?.     C). Which
           is the  first negative number in  this sequence?,    d. In which position

           did the first  negative number occur in this sequence?

19.   a )What is the common difference of the arithmetic sequence
          -100,-96,-92,...?       b)Check whether Zero is a term in this sequence.   
           c) Which is the first positive  number in this sequence?
20.  a). Write the arithmetic  sequence with first term 10 and common
            difference 4?      b) Write the difference of the terms in the same
           position of the above sequence and the arithmetic   sequence  
           11,17,23,....?        c) Find the sum of first 20 terms of the sequence
          thus obtained?
21. a)  Write the sequence of perfect squares which are even.        
       b) Is it an arithmetic sequence?        
22. a). The sum of first 9 terms of an arithmetic sequence is 360.
      b  )What is its 5th term?    c)  If the sum of first 5 terms is 100 , What is
         its third term?   d) What is the common difference of this sequence?     
        e) Write the sequence .
23. a ) Find the sum of first 30 natural numbers  .  b) Find the sum of first 30
        multiples of 6?  c) Write the algebraic form of the sequence obtained by
        subtracting 2 from the multiples of 6?    d) Find the sum of first 30 terms
        of this sequence?
24  The algebraic expression of an arithmetic sequence is 8n+5.  a ) What is
      the common difference of this  sequence?     b) What is the difference
      between the smallest four digit number and largest three digit  number
      in this  sequence
25. Consider the arithmetic sequence 4,6,8 ...
     a) What is the 5th term in the sequence?   b) Write the ratio between the
        first and third terms of this sequence?   c) Write the ratio between the
        fifth term and 15th  term of this sequence?   
26. a) Which is the first number above 200 which leaves a remainder 3 on
      division by 7?    b) How many such numbers are there between 200 and 
     400?   c) Find the sum of these numbers?
27. a). Write the first three digit number which is a multiple of 9.     b) Write the
      sequence of all three digit  numbers which are multiples of 9.
     c) How many numbers are there in the above sequence ?
     d) Find the sum of all these numbers.
28.  X  +  5  ,  2X – 1  ,   2X  +  3 ...  are three consecutive terms of an arithmetic
    sequence . Find the value of  X ?   b ). Find the sequence ?    c ). Find the 
    21st  term of this sequence ?


29.      4
           8    12
          16   20    24
          28   32    36   40
           ... ... ... ... ...
           ... ... ... ... ... ...
a) Write the next two rows in this pattern .
b) Write the first and last terms of the 11 th row.
30.                2
               4    6    8
      10   12   14  16  18
       .  .  .  .  .  .  .  .  ..
a) Write the next line in this pattern.
 b) How many numbers are there in the 10th row?
c)  What are the last and first terms in the tenth row ?
Hint:
c) Identifies the last terms as  2x1², 2x2²,    2x3²,...                                                                         
    Last term in the 10th row =2x10²=200                                      
    First term in the 10th row = 2x 9² + 2=164                      
31.  Write an arithmetic sequence with common difference as 6 .  Is the
       difference between any two terms  can be 500  ? . 
32.  Write an arithmetic sequence which leaves remainder 1 on dividing by 6 .
        Is 2017 can be a term of this   sequence ?
33.  7,  a  ,  b,  c,  d,  37  are first 6 terms of an arithmetic sequence ,  Find the
       value of   a,  b,  c,  d ?
34.  15,   a  ,  29 are  three consecutive  terms of an arithmetic sequence ,
       Find the Value of    a  ?  Can 345  be a term of this sequence?

35.  Some chairs are arranged in a hall as an arithmetic sequence .  47 chairs
      in the 6th row , 75 chairs in the 10th  row.    a).   Find the number of chairs
      in the first row ?   b).   Find the number of chairs in the 16th row ?
36. The sum of first n  terms of an arithmetic sequence is 3n2  +  2n Find the
      first term ?  Common difference ?   and   algebric form of this sequence ?
37.  Find the number of all  three digit numbers  which are divisible by 7 ?
38.   How many numbers are there between 200 and 500 which leaves
       remainder 3 on dividing by 9 ?
39.   How many terms are there in the sequence 10, 17, 24.......................... .346. 
40.  The algebraic form of an arithmetic sequence is 3n−5. Write the sequence
        What is its tenth term.  Is 231 a  term of this sequence
41.   The 8th term of an arithmetic sequence is 40. Calculate the sum of first 
       15  Terms ?          
42.   Write the algebraic expression of the sequence  3, 6, 12, 24,..................                                                                                                        
43.   20 is a term of an arithmetic sequence with common difference 3.  Can
        the sum of any 11 terms of  this  sequence be 517 ?  why?                                                                                            
 44.   The tenth term of an arithmetic sequence is 65 and its 15th term is 80.
         Is 200  a term of this  sequence ?    
 45.   How many 3 digit numbers are there which leaves remainder 5 on
         dividing by 7                             
46.   The angles of a pentagon are in an arithmetic sequence. Find the angles ?
 47.  There are 20 terms in an arithmetic sequence .   Sum of first term and
        last term is 88.  Find the   sum of    10th term and 11th term ?   If 10th term
        is 42 find  11th term ?  Find the sequence ?
48.  The difference between 12th term and 7th term is  50  and its 4th term
      is  16.    Find the common   difference ?    First  term and the sum of
     first n terms ?    

   
49.      4, 9, 16,25, ........    write the nest two terms of this sequence and Find the
         algebraic form

50.                                             1
                                           2     3       4
                                  5       6     7       8      9.
                   ....................................................
 a).    Write the next two line.   b).  Find the first number in the 11th row 
  c).   Find the lst number in the 11th row
 d).    Find the sum of all numbers  from first  row to 11th row.
51.    If the sum of three consecutive terms of an arithmetic sequence is 24
         and their product is 224. Find the terms?
52.   The second and third term of an arithmetic sequence  is  b, c Find  the
        first term  and fourth term ?
53.  The 12th term of an arithmetic sequence is 50 and sum of its first 12 term
      is 336. a). Find the first term ?       b). Find the common difference ?
          c). Is 478 a term of this sequence ? Give reason ?
54.  The sum of three consecutive terms of an arithmetic sequence is 30 and
        their product is 840 . Find the numbers ?
55.  Three times of the third term of an arithmetic sequence is equal to  five 
       times of the fifth term .   Find the 8th  term?
56.    nth  term of an arithmetic sequence is 3 + 4n
          a.  Find the 10th term ?   b ). Which term will we get if we add 132 to
             10th term ?
57.    The difference between 7th and 2nd term of an arithmetic sequence is 20. 
          a.  Find the common difference ?
          b. Its 3rd term is 9  How many terms gives the sum  as 153 ?  (Form  a
              second degree equation )

 58.   The product of first two consecutive terms with common difference  5 is
         266.  Find the sequence ?
59.    Sum of first five terms of an arithmetic sequence is 85  and sum of first
         10 term is  320 .  Find the sequence .
60.    Sum of first 7 terms of an arithmetic sequence is 112 and the sum of next
         seven terms  are 259.  Find the   sequence ?
61.   The expense for digging a well for the first one metre is 500 rupees, 50 
        rupees more for the next metre and  so  on.  The total length of the well is
        15 metre.   How much is needed for digging the last metres of the well.   
         What is total expense for digging the well?
62.   Write the sequence formed by the integer terms of the arithmetic
        sequence  19/8, 11/4,  25/8,......  is 47 can  be   a term of this sequence ?
63.    Prove that the squares of all the terms of the arithmetic sequence
      4, 7, 10, ....   belong to the sequence?
64.  The difference between 7th and 2nd terms of an arithmetic sequence is 20.
        Find the common difference ?  Its 3rd term is 9  How many terms gives
       the sum 153.
65.    The difference between the 15th term and the 5th term of an A.S is 40.
          Which number is to be added to its 12th term to get the 20th term?
          Find the difference between its first term and 21st term?
66.    When 60 is added to the first term of an A S we get its 11th term.
         Which number should be added to its  first term to get the 19th term ?
67.    52  X  54  X  56   X  .......................  X 52n     =   (0.008)-30    Find the value of  n
68     Write  two A S with  100 as the sum of first  four terms
69.    If the sum of first 7 terms of an A S is 49 and the sum of first 17 terms
        is 289.  Find the sum of first  n  terms
70     If the  nth term  of an A S is  2n + 1 .   Find the sum of first n terms
71     Find the 6th term from the end of the A S  17,  14,  11, ..............  , -40.



          is the ratio of the third term to the   fifth term ?
73.    The sum of the first 5 terms of an A S is 100  and the sum of First 10
         terms is 350.    Find the sum of First   n  terms
74     In an arithmetic sequence the ratio of  5th term to 7th term is 11 : 15
         and its 10th term is 42, find the  common difference and sequence?  
75.    The difference between the sum of  first 20 terms and the sum of next
         20 terms  of an arithmetic sequence is 1600. Find the common difference
         If the 7th term is 30 find the sequence.   
76.   Sum of first 6 terms of an A S is 162 and the sum of first 10 term is 430.
         Find the common difference?   First term?      





 
MATHEMATICS  OF CHANCE

1.   A  box contains 3 black balls and 7  white balls.  Another box
    contains one black and one white  more.  The probability of 
    getting a white  ball from which box is more ? 
    (White ball from First = 7/10 , White ball from second = 8/12 = 2/3,  7/10. 2/3 →21, 20
      First box is better choice )
2. One is asked tosay a two digit numbe.  (10,11,12...... 99,   n = 90)
     a. What is the probability of it being a perfect square (Ans = 6/90 )
        bWhat is the probability of it being a multiple of 5  (Ans = 18/90 )
      c. hat is the probability of bothdigits  being the same (A = 9/90 )
 3.  In class X A has 25 boys and 15 girls, in X B, there are 10 boys
     and 20 girls. One student is to be selected from each class.
     a. What is theprobability of both being boys  ( A = 250/1200)
       b.  What is theprobability of both being girls  ( A = 300/1200)
       c. What is theprobability of one boy and one girl (A= 650/1200 )
     d. What is the probability of atleast one boy (A= 900/1200)
4.  Arun tossed two coins simultaneously. Find the probability 
     of getting  ( HH,  HT,  TH,  TT )
        a. One head  (A  = 2/4 = 1/2 )
     b. Two head  ( A = 1/4)
     c. Atleast one head  (A = 3/4)
       d.  Atmost one head  ( Two heads are not needed  A= 3/4)
5.  A box contains some red balls and some green balls.  
     Probability of getting  red ball is 3/7. What is the probability
     of getting green balls? (Ans = 1-3/7 = 4/7)
6. A bag contains some black balls , some white balls and some
    green balls. Probability of getting black ball is 2/5, probability 
    of gettinmg a white ball is 1/3, Find the probability of getting 
    a green ball?{Ans = 1-(2/5+1/3) = 4/15}
7.  A bag contains  some black balls and some white balls. No of           white ball is 3 more than twice the black balls.  Probability of 
     getting white ball is 5/7.  Find the number of black balls and 
     white balls ? (Ans = No of black balls = x, No. of white ball = 2x+3, 
      Total ball = 3x+3,   Black ball = 6, White ball = 15 ).
8. One box contains 8 black balls and 12 white balls.  Another 
    box contains 9 black and 6 white balls.  One ball is taken
     from each box . (Ans. Hints Total pairs = 20x15= 300 )
    a. What is the probability of getting both  black  (A = 6/25 )
      b. What is the probability of getting both  white  (A = 6/25 )
      c. What is the probability of getting one black and one white
         (A = 39/75)
9.  A box contains four slips numbered 1,2,3,4 and another box
      contains three slips 1,2,3.  If one slip is taken from each box
             (1,1), (1,2), (1,3)
                   (2,1), (2,2), (2,3)
                   (3,1), (3,2), (3,3)
                   (4,1), (4,2), (4,3)  Total = 12.
    a. What is the probability of the product being odd ? 
        ( (1,1)  (1,3)  (3,1)   (3,3) ) (Ans  = 1/3 )
     b. What is the probability of the product being even ? (A=2/3)
      c. What is the probability of getting sum as 5 ?  (A = 3/12 =1/4)
       d. Both digit are same   (A = 1/4 )

10. Two dice with faces numbered from 1 to 6 are rolled together.  
       a. What are the possible sums? ( (1,1), (1,2), (1,3) .... (2,1), (2,2), (2,3 ...
           .......(6,1), (6,2), (6,3), (6,4),(6,5), (6,6) ) Total 36
          b. What is the probability of getting sum as 5 ?  (A= 1/9)
          c.    What are the possible sums ? ( 2, 3,4,5,6,7,8,9,10,11,12 )
          c.  Which of these sums has the maximum probability  (A=7)

   


SECOND DEGREE EQUATIONS

1  . Is it possible to make a rectangle with area and perimeter 
     as equal to 18units, if possible find the length and breadth? 
        Ans.  ( Hints.  Find b² - 4ac  ( yes it is possible ) by solving  l = 6, b = 3 )

2.  The square of a term in arithmetic sequence  2, 5, 8, ..... is 2500.
    what is its position ? (Which term's square is  2500 )
    Ans. (Hints.  Find the algebric form  and its square = 2500, by solving  n =  17 )
3. The common difference of an arithmetic sequence is 4 and 
     its product of first and third term is  84 find the first term 
     and sequence
         Ans. (Hins. Terms  x,  x+ 4 , x+8,    x (x+8) =84  by solving  x = 6,  terms  6,10, 14 ........  )
4.  How many terms of the arithmetic sequence  2, 6, 10,.......
     must be added to get 288.
     Ans. (Hints.  n/2 ( x1 + xn ) = 280,  find xn  and by solving  n = 12 )
5.  Altitude of a triangle is 3cm more than its base and its area is 
     44 cm² Find the base and altitude ?
     Ans. (Hints. base = x, altitude x+3, ½ x(x+3)= 44,   Base = 8, Altitude = 11 )
6. Product of two consecutive multiples of 4 is 480 Find the 
    numbers Ans. (Hints First no. = x, second no. x+4,  x(x+4) = 480, by solving nos = 20,24)
7. A 56 cm long wire is bent into a rectangle and the distance
     from one corner to another corner is 20 cm . Find the length 
     and breadth of the rectangle ?
       Ans. (Hints 2(l+b) =56,  l+b = 28, l. = x, b= 28-x,  hypotenuse=  20,  l² + b² = h², l=16, b =12)
8.  For completing a work  Babu needs 5 days more than Abu  
     claimed.  They together did the work in 6 days.  Find the
     number of days required by each person to complete the work 
     superately?
     ( Hints. Abu need x days, Babu need x+5 days,  1/x + 1/(x+5) =1/6 , x² -7x-30=0 , x= 13 )
9.  If the sum of reciprocals of two consecutive even number  is  
     9/40. Find the numbers 
    (Nos x, x+2 , 1/x = 1/(x+2) = 9/40,   Nos. = 8, 10 )
10. 12x² + 4kx + 3 = 0  has only one solution find the value of K?
       ( a= 12, b= 4k, c=3 , b² -4ac = 0,  K = +3, -3 )
11. In a two digit  number the digit in the unit place is 1 more than 
      the twice of the digit in the tenth place. If theproduct of the 
     digis are 36, Find the number  ( Ans. Hint  Digit in the tenth place = x,  Digit in
        the unit  place = 2x+1, No.= 10x+2x+1=12x+1, x(2x+1) = 36, x = 4, No 49  )
12. Sanu wrote a two digit number  and he noticed that the product 
     of the digit is 14.  When he added 45 to the number,  the digits
     are reversed. Find the original number  (Ans. Hint Digit in the 10th place =x,
        digit in the unit place = 14/x ,  Original No. 10x + 14/x,   Reversed No. 140/x + x ,
       10x + 14/x +45=140/x + x by multiplying by x , x² +5x-14 =0 , No. 27 )
13. If the total number of a diagonals of a polygon is 90,  find the 
      number of sides of the polygon (Number of sides n , diagonal = n(n-3)/2 )
14. If  x² + ax + b = 0 , has only one solution Prove that a² = 4b,
      If   x² + ax + 100 = 0 has only one solution find the value of a
      If  x² + 18x + b = 0 has only one solution find the value of b
      (Ans. Hint. a = 1, b= a, c= b, b² - 4ac = 0  )
15. Can the sum of a number and its reciprocal be 3½, Why
      (No. = x, Reciprocal 1/x,  x +1/x = 7/2)
16. Find the discriminant of  the following 
      a,   x² + 4 = 0
      b.  x² + 4x = 0
      c.  x² - 4  = 0  (find Discriminant b² -4ac )
17.  Raju solved a second degree equation as stated below can 
       you complete the problem by  filling the blanks.
        x² - 14x  = 32
       x²  - 14x + ......  = 32 + ......
       (x -  ..... )²   =   .......
        x - .....     =  ,,,,,
        x =  .....   or  .....
18.  A bus travels a distance of 300km at a constant speed.  If the
       speed of the bus is increased by 5km/hr, the journey would
       have taken 2 hours less.  Find the original speed of the bus?
        (Speed =x, Distance = 300, Time = 300/x , then s= x+5, S=300, T= 300/(x+5) ,
          then 300/x-  300/(x+5) = 2 , by solvindg  x = 25 )
19.  The sum of the ages of a man and his son is 45, The product 
      of their ages before 5 years is 124.  Find their present ages
      (Present age of Man = x, Present age of son = 45-x, Age of man before 5 year = x-5,
        Age of son before 5 year = 40-x, (x-5) (40-x) = 124, Age of man x=  36, Age of son = 9 )
20. Altitude of a right angled triangle is 7 cm more than its base 
      and the hypotenuse is 3 cm more than twice its base. Find  
      the sides of the triangle? (Base = x, Altitude = x+7, Hypotenuse = 2x+3,
           Base² + Altitue² = Hypotenuse² ,  base = 5, Altitude =12 , Hypotenuse =13 )
        

TRIGONOMETRY 

1.     Sin A =  5/13 , Find CosA  and Tan A ?
2.     If Sin A  = 0.6 Find the value of Cos A  and Tan A ?
3.    In Δ ABC ㄥC = 90 , BC = a, AC = b  and AB = c , Show that 
       Sin² A + Cos² = 1,  If  SinA = 0.8  Find the value of Cos A?
4.    In Δ ABC  AB = 12 cm  and AC = 10 cm and  ㄥA = 60 , 
       Find the area of the triangle ?
5.     In Δ ABC  AB = 8 cm  and AC = 10 cm and  ㄥA = 120 , 
        Find the area of the triangle ?
6.    The area of a parallelogram  is 30 sq.cm , one of its side is 
       5 cm and one of its angle is 60 degree 
       a. Find the height of the parallelogram ?
       b. Find the length of the other side?
7.    Two sides of a parallelogram are 12cm and 10 cm and angle 
       between them is 30 degree find the  area of the parallelogram ?
8.    The sides of an equilateral triangle are  6 cm long. Find the 
       radius of the circumcircle ?
9.    The length of the chord of a circle is 10 cm long and the angle 
       between chord and a diameter is  30 degree find the radius of
       the circle ? 
10.  One angle of a triangle is 110 degree and the  side opposite to 
       it is 6 cm long . What is its circum radius ?
      ( Sin70 = 0.94,  Cos70 = 0.34 and  Tan 0 = 2.75 ) 
11. The sides of a parallelogram are  10 cm and  6 cm long and 
      angle between them is 30 degree Find the length of the  
      diagonals ?
12. A ladder leans against  a wall and the ladder touched at the top
      of the wall its foot is 2m away fromthe wall  and it make 35 
      degree angle with the ground .  Find the height of the wall and 
      length of the ladder? (Sin 35 = 0.57, Cos 35 =0.81, Tan35=0.7)
13. PA and PB are two tangents drawn from 8 cm away from the 
      centre of a circle and the angle between the tangents are 70 
      degree. Find the radius of the circle and length of the tangents ?
14. The anglebetween height and slant height of a cone is 60 
      degree and its slant height is  20 cm . Find the total surface 
       area  volume of the cone ? 
15. In ΔABC, AB = 8 cm , BC = 10 cm  and ㄥB = 60 degree
      Find AC
16.  In ΔABC, AB = 12 cm   and ㄥA =  ㄥB = 30 degree 
      a. Find the perimeter of the triangle ?
      b. Find the area of the triangle?
      c. Find the ratio of the sides of the triangle?
17. In ΔABC, AB = 10 cm  and ㄥA = 50, ㄥB = 65 degree
      Find the area of the triangle ( Sin 50 = 0.77, Sin65 = 0.91) 
18.  A verticle tree is broken by the wind. The top of the tree 
       touches the ground and make an angle  30degree with it.  
       If the top of the tree touches the ground  30 maway from 
       its foot. Find the actual height of the tree ?
19. A 1.5 m tall boy sees the top a building at an elevition of  
      35 degree after walking 20 m towards the building he sees
      the top of the building atan elevition of 55 degree
      (Tan35 = 0. 7,  Tan 55 = 1.4 )
      a.  Draw a rough figure
      b. Find the height of the building
      c.  Find the distance between boy and building at present?
20. Standing  50 m away from a level road Anu sees her friend 
      Banu and Chippy at 48 degree and 57 degree angle of elevation
      in the flat. If so what is the height difference in the position of 
      Banu and Chippy?   (Tan 48 = 1.1,  Tan 57 = 1.5 )
21. Two building in a plane ground are 30 m apart.  From the top
      of the smaller building one sees the base of the building at a 
      depression of 50 degree and its top at an elevation of 35degree.
      ( Tan 50 = 1.2 ,  tan 35 = 0. 7)
       a. Draw a rough figure
       b. Find the height of the smaller building
       c. Find the height of the bigger building
 22. Two verticle buildings are on a levelground, the smaller 
       one has height 20m,  From the top of the larger building 
       a boy sees the top of thesmaller building at a depression 
       of  55 degree  and bottom of  the smaller  building at a 
      depression of 70degree Find the height of the larger building?
23.  A man 1.7 m tall, standing at the foot of a tower  sees the top           of a hill 40 m away at an elevation of 60 degree.  On climbing
       to the top of the tower  he sees the top of the hill at an elevation
       of 50 degree . Find the height of the hill and tower ?
       ( Sin 50 = 0.77,  Cos 50 = 0.64,   Tan50 = 1.19 )
24. A 1.6 m tall boy sees the top of a building under construction 
      at an elevation 30 degree.  The building is completed 10 more 
      meters  to its  height,  and t hen the boy sees the top of the 
      completed building at an elevation of 60 degree  from the same 
      spot .  Find the height of the building 
25. A man 1.7 m tall looks down from the top of a light house  
     25m heigh and sees a boat at an angle of depression of 35 
     degree.  How far is the boat from the foot of the light house ?