# Help verifying this ID?

• March 23rd 2011, 09:18 AM
generalmeow
Help verifying this ID?
sin³(3x) = ½(sin(3x))(1-cos(6x))

I'm just stumped...everything I've tried has turned into a complete mess. Thanks a bunch for any ideas!
• March 23rd 2011, 09:20 AM
TheEmptySet
Quote:

Originally Posted by generalmeow
sin³(3x) = ½(sin(3x))(1-cos(6x))

I'm just stumped...everything I've tried has turned into a complete mess. Thanks a bunch for any ideas!

$\displaystyle \sin^3(3x)=\sin(3x)\sin^2(3x)=\sin(3x)\left[\frac{1}{2}(1-\cos(6x))\right]$
• March 23rd 2011, 09:21 AM
Chris L T521
Quote:

Originally Posted by generalmeow
sin³(3x) = ½(sin(3x))(1-cos(6x))

I'm just stumped...everything I've tried has turned into a complete mess. Thanks a bunch for any ideas!

For this one, show that RHS implies LHS.

For a hint, reference the spoiler. :)

Spoiler:
$\sin^2(\alpha)=\tfrac{1}{2}(1-\cos(2\alpha))$

EDIT: TES beat me!