Question

x apatine cadranului 4 , cosx=radicaj2/2 ,aflati sinx

Answer 1

$\it x\in(\dfrac{3\pi}{2},\ 2\pi),\ cosx=\dfrac{\sqrt2}{2} \Rightarrow x=-\dfrac{\pi}{4}\\ \\ \\ sin\Big(-\dfrac{\pi}{4}\Big)=-sin\dfrac{\pi}{4}=-\dfrac{\sqrt2}{2}$