Integration Question (1 Viewer)

[FroZenWaffleS]

Find the definite integral from 0 to pi/2 of 4 cos ^3 x dx

assuming that cos3 theta = 4 cos ^3 theta - 3cos theta

EDIT: Also the integral from 0 to 1 of 2 ^x dx

 

[pLuvia]

Are you sure it's not

cos 3@ = 4cos 3@ - 3cos@

Because cos³@ is quite hard to integrate

 

[acmilan]

cos3@ = 4cos³@ - 3cos@

4cos³@ = cos3@ + 3cos@

int 4cos³@ = int (cos3@ + 3cos@) d@ = (sin3@)/3 + 3sin@

sub in pi/2 into that and you should get the answer