I don't understand why: (cosx)^2 (sinx)^2 = (1/4)(sin2x)^2 what identities are used here? Thanks!
Follow Math Help Forum on Facebook and Google+
$\displaystyle \sin 2x = 2\sin x\cos x$
(cosx)^2 = ( (1 + cos2x) / 2 ) (sinx)^2 = ( (1 - cos2x) / 2 ) then, in the end 1 - (cos2x)^2 becomes (sin2x)^2
View Tag Cloud