Question

Find the point (x, y) on the unit circle that corresponds to the real number 5pi/6. Use it to evaluate cos t.

cos t = (-sqrt(3)/2)?

Answer 1

by definition, we can write:
\[\Large \begin{gathered}
x = \cos \left( {\frac{{5\pi }}{6}} \right) = ...? \hfill \\
\hfill \\
y = \sin \left( {\frac{{5\pi }}{6}} \right) = \sqrt {1 - {{\left\{ {\cos \left( {\frac{{5\pi }}{6}} \right)} \right\}}^2}} = ...? \hfill \\
\end{gathered} \]

Answer 2

for the y-coordinate I choose the positive square rooth since your point is at II quadrant