Evaluate the following integrals:
∫ sin5 x dx = ∫ 
= ∫ 
{ since sin2x + cos2x = 1}
= ∫ 
= ∫( sin
( 
= ∫( sin
( 
{ since sin2x + cos2x = 1}
= ∫( sin
= ∫ sin
(separate the integrals)
We know , d(cos x) = -sin xdx
So put cos x = t and dt = -sin xdx in above integrals
= ∫ sin
= ∫ sin
= ∫ sin
= ∫ sin
= ∫ sin
= 
( since ∫xⁿ dx = 
+ c 
)
Put back t = cos x
= 
= 
= -[
2