Cos kuadrat x +sin kuadrat x=

[tex]\displaystyle \boxed{\boxed{\cos^2x+\sin^2x=1}}[/tex]

[tex]\displaystyle \text{pembuktian :}\\\sin x=\frac{y}{r}\wedge\cos x=\frac{x}{r}\\\\\sin^2x+\cos^2x=\frac{y^2}{r^2}+\frac{x^2}{r^2}\\\sin^2x+\cos^2x=\frac{y^2+x^2}{r^2}\\\sin^2x+\cos^2x=\frac{r^2}{r^2}\\\boxed{\boxed{\sin^2x+\cos^2x=1}}[/tex]

Identitas Trigonometri.

cos² x + sin² x = 1

Pembuktian :

cos² x + sin² x = 1
(x/r)² + (y/r)² = 1
(x²/r²) + (y²/r²) = 1
(x² + y²)/r² = 1
r²/r² = 1
1= 1