Question

Jika tn x= 1/t Tentukan nilai dari:
a.sin2x
b.cos2x

Answer 1

Tan x = 1/t
y = 1 , x = t
r = √(x²+y²)
r = √(1+x²)
sin x = y/r = 1/(√(1+x²)
cos x = x./r  = x/(√1+x²)
.
sin 2x = 2 sin x cos x =  x/(1+x²)
cos 2x = 2(cos x)²  - 1= 2x²/(1+x²)  - 1