Question

Calculati cos x, stiind ca sinx= 1/3 si x∈(0,/2).

Answer 1

Din formula fundamentala a tigonometriei: $sin^{2}x + cos^{2}x = 1$ => $cosx = \sqrt{1-sin^{2}x}$ => cosx = $\frac{2 \sqrt{2} }{3}$