buktikan bahwa : [tex] {cos}^{2} x \: - {sin}^{2} x = 1 - 2 {sin}^{2} x[/tex]

Trigonometri

cos^2 x - sin^2 x = 1- 2sin^2 x

karen
sin^2 x = 1- cos^2 x
maka

cos^2 x - (1-cos^2 x)
= cos^2 x - 1 + cos^2 x
= 2 cos^2 x - 1