How do you simplify $sin^4 x - cos^4 x$ ?

Question

8400 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-02-19T15:28:20

$sin^4(x)-cos^4(x)=-cos(2x)$

Using the following

We have:

$sin^4(x)-cos^4(x) = (sin^2(x)+cos^2x())(sin^2(x)-cos^2x())$

$=(1)(-cos(2x))$

$=-cos(2x)$

How do you simplify sin^4 x - cos^4 xsin^4 x - cos^4 x?