

 Solution :
 
  Question 3. cos 2
  
   x
  
  cos 4
  
   x
  
  cos 6
  
   x
  Solution :
 
  Question 3. cos 2
  
   x
  
  cos 4
  
   x
  
  cos 6
  
   x
  
 Solution :
 
  Question 4.
 
  sin
  
   3
  
  (2
  
   x
  
  + 1)
  Solution :
 
  Question 4.
 
  sin
  
   3
  
  (2
  
   x
  
  + 1)
 
 Solution :
 
  Question 5.
 
 sin
 
  3
 
  x
 
 cos
 
  3
 
  x
  Solution :
 
  Question 5.
 
 sin
 
  3
 
  x
 
 cos
 
  3
 
  x
 
 Solution :
 
  Question 6. sin
  
   x
  
  sin 2
  
   x
  
  sin 3
  
   x
  Solution :
 
  Question 6. sin
  
   x
  
  sin 2
  
   x
  
  sin 3
  
   x
  
 Solution :
 
  Question 7.
 
  sin 4
  
   x
  
  sin 8
  
   x
  Solution :
 
  Question 7.
 
  sin 4
  
   x
  
  sin 8
  
   x
  
 Solution :
 
 It is known that,
sin A . sin B = 12cosA-B-cosA+B
∴∫sin4x sin8x dx=∫12cos4x-8x-cos4x+8xdx
=12∫cos-4x-cos12xdx
=12∫cos4x-cos12xdx
=12sin4x4-sin12x12+C
 
  Question 8.
  Solution :
 
 It is known that,
sin A . sin B = 12cosA-B-cosA+B
∴∫sin4x sin8x dx=∫12cos4x-8x-cos4x+8xdx
=12∫cos-4x-cos12xdx
=12∫cos4x-cos12xdx
=12sin4x4-sin12x12+C
 
  Question 8.
 
 Solution :
 
  Question 9.
  Solution :
 
  Question 9.
 
 
 Solution :
 
  Find the integrals of the following functions in Exercises 10 to 18.
  Solution :
 
  Find the integrals of the following functions in Exercises 10 to 18.
 
 Question 10. sin
  
   4
  
   x
  
  Solution :
  Question 10. sin
  
   4
  
   x
  
  Solution :
 
 Question 11. cos
  
   4
  
  2
  
   x
  
  Solution :
 
  Question 12.
  Question 11. cos
  
   4
  
  2
  
   x
  
  Solution :
 
  Question 12.
   
 Solution :
 
  Question 13.
  Solution :
 
  Question 13.
 
 
 Solution :
 
  Question 14.
  Solution :
 
  Question 14.
 
 
 Solution :
 
  Question 15. tan
  
   3
  
  2x sec2x
  Solution :
 
  Question 15. tan
  
   3
  
  2x sec2x
 
 Solution :
  Solution :
 
 Question 16. tan
  
   4
  
   x
  
  Solution :
 
  Question 17.
  Question 16. tan
  
   4
  
   x
  
  Solution :
 
  Question 17.
 
 
 Solution :
 
  Question 18.
  Solution :
 
  Question 18.
 
 
 Solution :
 
  Integrate the following functions in Exercises 19 to 22.
 
  Question 19.
  Solution :
 
  Integrate the following functions in Exercises 19 to 22.
 
  Question 19.
 
 
 Solution :
 
  Question 20.
  Solution :
 
  Question 20.
 
 
 Solution :
 
  Question 21. sin
  
   −1
  
  (cos
  
   x
  
  )
  Solution :
 
  Question 21. sin
  
   −1
  
  (cos
  
   x
  
  )
 
 Solution :
  Solution :
 
 
 Question 22.
  Question 22.
 
 Solution :
 
  Choose the correct answer in Exercise 23 and 24.
  Solution :
 
  Choose the correct answer in Exercise 23 and 24.
 
 Question 23.is equal to:
  Question 23.is equal to:
   
A. tan x + cot x + C
B. tan x + cosec x + C
C. − tan x + cot x + C
D. tan x + sec x + C
Solution : Therefore, option (A) is correct.
 
  Question 24. is equal to:
 Therefore, option (A) is correct.
 
  Question 24. is equal to:
   
A. − cot ( e x x ) + C
B. tan ( xe x ) + C
C. tan ( e x ) + C
D. cot ( e x ) + C
Solution : Let I = Let
 
  e
 
   x
  
  x
 
 =
 
  t
 
 Therefore, option (B) is correct.
 Let
 
  e
 
   x
  
  x
 
 =
 
  t
 
 Therefore, option (B) is correct.
  


