Question

Sa se calculeze sin120*+cos 150*

Answer 1

$\displaystyle\\ \sin120^o + \cos150^o = \\\\ \sin(180^o-60^o) + \cos(180^o-30) = \\\\ \sin60^o + \Big(- \cos30^o\Big)=\\\\ \sin60^o-\cos30^o = \frac{\sqrt{3}}{2}-\frac{\sqrt{3}}{2}=\frac{\sqrt{3}-\sqrt{3}}{2}=\frac{0}{2}=\boxed{\bf 0}$

Answer 2

$\it sin120^o+cos150^o=sin(180^o-120^o) -cos(180^o-150^o)= \\ \\ = sin60^o-cos30^o=\dfrac{\sqrt3}{2} -\dfrac{\sqrt3}{2} = 0$