Question

I usually get stuck in questions of integration like integrate sin 3 x (upper limit: pi/2, lower limit:0). please explain the step when we take sinxdx as - dcosx in the integration process

Answer 1

let me show u
the differentiation of d/dx(cosx) = -sinx
 sinx dx = -cosx
now ur Q. is integration of sin3xdx= -cos3x/3
here 3 is taken in divide because it is multiple with 3
now limit 0 to pi/2
(-cos3*pi/2 + cos0)
cos(270)=0
cos0=1
so 0+1=1
answer is 0