# How do you evaluate #sec^-1(-2/sqrt3)#?

##### 1 Answer

Aug 18, 2016

150 degrees or 5

#### Explanation:

sec

Which is the angle whose cosine is -

Draw an equilateral triangle and cut in half.

The ratio of the sides of the right angle triangle are 1:2::

So the angle whose cosine is +

From the cosine graph the angle whose cosine is-