How do you find the integral of sin^2 (ax)sin2(ax)?

1 Answer
Mar 22, 2018

int sin^2(ax) dx= ( ax-sin(ax)cos(ax) )/(2a)+Csin2(ax)dx=axsin(ax)cos(ax)2a+C

Explanation:

Use the trigonometric identity:

sin^2(ax) = (1-cos(2ax))/2sin2(ax)=1cos(2ax)2

So:

int sin^2(ax) dx= int (1-cos(2ax))/2dxsin2(ax)dx=1cos(2ax)2dx

int sin^2(ax) dx= 1/2 int dx -1/2 int cos(2ax)dxsin2(ax)dx=12dx12cos(2ax)dx

int sin^2(ax) dx= x/2 -1/(4a) int cos(2ax)d(2ax)sin2(ax)dx=x214acos(2ax)d(2ax)

int sin^2(ax) dx= x/2 -1/(4a)sin(2ax) +Csin2(ax)dx=x214asin(2ax)+C

int sin^2(ax) dx= x/2 -1/(2a)sin(ax)cos(ax) +Csin2(ax)dx=x212asin(ax)cos(ax)+C

int sin^2(ax) dx= ( ax-sin(ax)cos(ax) )/(2a)+Csin2(ax)dx=axsin(ax)cos(ax)2a+C