# Chain rule or Power rule or both? Trig derivative

• Dec 12th 2007, 04:13 PM
Truthbetold
[solved] Chain rule or Power rule or both? Trig derivative
$y=\sin^2{x}$

Do I use the power rule for 2 sin x
or
the chain rule for 2sin x times cos x
or
the power chain rule for 2 sin x times 1?

Thank you!
• Dec 12th 2007, 05:15 PM
Krizalid
$f'(x)=2\sin x\cdot(\sin x)'.$

Chain rule, that's all.
• Dec 13th 2007, 05:14 AM
colby2152
Quote:

Originally Posted by Truthbetold
$y=\sin^2{x}$

Try treating $y=\sin^2{x}$ as $g(x)={f(x)}^2$ where $f(x)=sin(x)$. Now find $g'(x)$.