help pls

[quartz temple]

cos2x = 1 - 2sin^2(x)

or u can make a traingle , find cosx and use
cos2x = 2cos^2 x - 1

[mighty heart]

Could u show how u did that please @quartz temple

[quartz temple]

theres formula cos2x = cos^2 x - sin^2x

[mighty heart]

I think I’m supposed to do it by drawing a triangle, u think u could show me how to do it by doing that?

[quartz temple]

no thats just basic formula cos2x = cos^2(x) - sin^2 (x)

and we know that cos^2 (x) + sin^2 (x) = 1
so cos^2(x) = 1 - sin^2(x)

so that formula wl become cos2x = 1 - 2sin^2 (x)