# Question e0579

Nov 5, 2016

For angles 0 <= theta <= 360°

theta = 180° - 45° = 135°
or
theta = 180°+45° =225°

#### Explanation:

${\sec}^{-} 1 = \frac{- \sqrt{2}}{1} = \frac{h}{o}$

The root angle is 45° - based on an isosceles triangle with sides in the ratio: $1 : 1 : \sqrt{2}$

Sec is negative in the 2nd and 4th quadrants.

So for angles 0 <= theta <= 360°

theta = 180° - 45° = 135°
or
theta = 180°+45° =225°#