Step-by-step explanation:
a) cos θ = √2/2
That is
[tex]cos\theta =\frac{\sqrt{2}}{2}=\frac{1}{\sqrt{2}}\\\\\theta=cos^{-1}\left ( \frac{1}{\sqrt{2}}\right )[/tex]
In degrees the values are 45° and 315°
[tex]\texttt{In radians values are }\frac{\pi}{4}\texttt{ and }\frac{7\pi}{4}[/tex]
b) cos θ = -√2/2
That is
[tex]cos\theta =\frac{-\sqrt{2}}{2}=-\frac{1}{\sqrt{2}}\\\\\theta=cos^{-1}\left ( -\frac{1}{\sqrt{2}}\right )[/tex]
In degrees the values are 135° and 225°
[tex]\texttt{In radians values are }\frac{3\pi}{4}\texttt{ and }\frac{4\pi}{4}[/tex]