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Hi, I need help trying figure out this problem: I'm trying to figure out the steps to get from one equation to another

Starting Equation:
$Y = X \cos^2 \theta \cos^2 (\frac \pi 2 - \theta)$

**missing steps**

Final Equation:
$Y = \frac X 4 \sin^2 2\theta$


If anyone can help I'd greatly appreciate it. Thanks!

DCabral242 wrote: Starting Equation:
$Y = X \cos^2 \theta \cos^2 (\frac \pi 2 - \theta)$

**missing steps**

Final Equation:
$ = \frac X 4 \sin^2 2\theta $

Welcome to BdMO forum! Please read how to use LaTeX from here http://www.matholympiad.org.bd/forum/vi ... p?f=25&t=2 , it's easy and fun.

$Y = X \cos^2 \theta \cos^2 (\frac \pi 2 - \theta)$
$ = X \cos^2 \theta \sin^2 \theta$
$ = \frac X 4 (2 \sin \theta \cos \theta)^2 $
$ = \frac X 4 \sin^2 2\theta $

Thank you so much!