I see Q2, -1/2 220 degree and Q3, -1/2 on 210 degree..

In the given unit circle, the x coordinate gives the cos value of an angle and the y cooridnate gives the sine value of an angle.
The sine and cosine value of a particular angle is,
[tex]\frac{-\sqrt[]{2}}{2}[/tex]From the given unit circle
[tex]\begin{gathered} \cos \frac{3\pi}{4}=\frac{-\sqrt[]{2}}{2} \\ \sin \frac{5π}{4}=\frac{-\sqrt[]{2}}{2} \end{gathered}[/tex]