Buktikan sin^2 x + cos^2 x = 1

Buktikan sin^2 x + cos^2 x = 1

Jawab:

sin^2 x + cos^2 x = 1
= sin^2 x + cos^2 x
= sin x.sin x + cos x.cos x
= cos (x - x)
= cos 0
= 1
{Terbukti}

Cara lain:

sin θ = a/r
cos θ = q/r

sin^2 θ = a^2/r^2
cos^2 θ = q^2/r^2

sin^2 θ + cos^2 θ
= (a^2/r^2) + (q^2/r^2)
= (a^2 + q^2)/r^2
r^2 = a^2 + q^2

(a^2 + q^2)/r^2
= r^2/r^2
= 1
{Terbukti}