Jawabanmu

2014-04-20T17:30:40+07:00
Tg x = p ; sin x = p÷√p²+1; cos x= 1:√p²+1

jadi cos2x - sin2x =
(cos²x-sinx) - 2 sinx cosx=
[(1:√p²+1)² - (p:√p²+1)²] - [2 (p:√p²+1)(1:√p²+1)]=
(1 - p² - 2p)÷(p²+1)

:)