# How do you evaluate using a calculator of cos^-1(-0.3218)?

Sep 3, 2016

cos^-1 (-0.3218) = 108.77°
cos^-1 (-0.3218) = 251.23°

#### Explanation:

You key it in exactly as it is written.

Use the shift/alt/2nd F key before the cos key, to use ${\cos}^{-} 1$

This is not the same as $\frac{1}{\cos}$

${\cos}^{-} 1$ is the way of finding which angle has a cos value of $- 0.3218$

cos^-1 (-0.3218) = 108.77°

or cos^-1 (-0.3218) = 251.23°