Question

Calculati sinx stiind ca 0*<x<90*
cosx=2/3

Answer 1

x ∈ (0; π/2) 
cos x = $\frac{2}{3}$

$sin^2x + cos^2x = 1$
$sin^2x = 1- cos^2x$
$sin^2x = 1 - \frac{2^2}{3^2}$
$sin ^2x= \frac{5}{9}$

sin x = +- $\sqrt{ \frac{5}{9} }$ 
x ∈ (0, pi/2)            
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 => sin x = $\sqrt{ \frac{5}{9} }$