Integral question ( finding volume):

Find the volume obtained by rotating the following curves bounded by:

y=sinx y=0 pi/2≤ x ≤ pi

I used cylindrical method because washer doesn't work in this case ( only one function)

Question

Integral question ( finding volume): 

Find the volume obtained by rotating the following curves bounded by:

y=sinx y=0 pi/2≤ x ≤ pi

 I used cylindrical method because washer doesn't work in this case ( only one function)

anonymous · Answer

Cylindrical gave me :  ∫(pi/2 to pi) 2pi (x) sinxdx but integration by part didn't give me the right answer and the answer key gave me   ∫pi(x)^2 dx which I don't understand from where it comes from.