Evaluate the $\sin$, $\cos$ and $\tan$ without using calculator? 
Evaluate the $\sin$, $\cos$ and $\tan$ without using calculator?
$150$ degree 

the right answer are $\frac{1}{2}$, $-\frac{\sqrt{3}}{2}$and $-\frac{1}{\sqrt{3}} $

$-315$ degree

the right answer are $\frac{1}{\sqrt{2}}$, $\frac{1}{\sqrt{2}}$ and $1$.

You can look up cos and sin on the unit circle.

The angles labelled above are those of the special right triangles 30-60-90 and 45-45-90.  Note that -315 ≡ 45 (mod 360).
For tan, use the identity $\tan{\theta} = \frac{\sin{\theta}}{\cos \theta}$.
