I feel like this is super simple, but I'm not getting it, can someone walk me threw the steps and maybe give me some pointers on what I should study to understand this concept fully.
We can use the cosine inverse (arccos) to find this angle (in degrees)
So...the angle A is
arccos(-.20) = A ≈ 101.54°
To find the radian measure use this conversion :
101.54 * pi / 180 ≈ 1.77 rads = 1.8 rads
