How do you prove $1-4sin^4(x)=cos(2x)(1+2(sin^2)x)$ ?

Question

4228 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-12-14T04:02:12

$(1 - 4sin^4 x) = (1 - 2sin^2 x)(1 + 2sin^2 x)$
Use trig identity:
$cos 2x = 1 - 2sin^2 x$ .
We get:
$(1 - 4sin^4 x) = cos 2x(1 + 2sin^2 x)$ . Proved

How do you prove 1-4sin^4(x)=cos(2x)(1+2(sin^2)x)1-4sin^4(x)=cos(2x)(1+2(sin^2)x) ?