find all angles between 0 and 180

Question

Find all angles θ between 0° and 180° satisfying the given equation. 

cos (angle) =5/7

Answer 1

Find all angles θ between 0° and 180° satisfying the given equation. 

cos (angle) =5/7

There is only one angle because cosine of angles in the range 90° to 180° is negative

 (They are located in second quadrant)

The angle can be found from a calculator arc cos(5/7) = 44.4153°