# Math Help - More Proving

1. ## More Proving

$cos^2(2x)-cos^2(x)=sin^2(x)-sin^2(2x)$

2. Originally Posted by Dragon
$cos^2(2x)-cos^2(x)=sin^2(x)-sin^2(2x)$
Typically we do stuff to one side to make it equal to the other, but this one is much faster using standard manipulations:
$cos^2(2x)-cos^2(x)=sin^2(x)-sin^2(2x)$

$sin^2(2x) + cos^2(2x) = sin^2(x) + cos^2(x)$

$1 = 1$

-Dan