# Special Triangles

How to find the trigonometric values of some special angles without using a calculator to approximate them.

1.  $\rhd$ Trig values of special angles (7:53)
Sal finds the trig values of $\frac{\pi}{4}$ on the unit circle using triangles.
2.  $\star$ Trig values of special angles
Students are asked to find the trig values of angles such as $-\frac{2\pi}{3}$ without using a calculator.