Calculus
posted by Juliet
differentiate:
y=sin^2(x) cos^2(x)
I have this:
y'= 2cosx + 2sinx
What do i do next??

Reiny
Ahhh, you might recognize that
cos^2 x  sin^2 x = cos 2x
so y=sin^2(x) cos^2(x)
=  cos 2x
dy/dx = 2sin 2x or 4sinxcosx
If you don't see that identity right away, then
dy/dx = 2(sinx)cosx  2cosx(sinx)
= 4sinxcosx or 2sin(2x) 
Anonymous
Oh! Thank you so much! I completely forget about the double angle identity!!! :)
THANKS!!!
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