Question

How do you evaluate `arccos (1/2)`?

Answer 1

Find arccos (1/2)

Explanation:

Trig Table gives:

`cos x = 1/2 --> x = pi/3 or 60 deg`

Trig unit circle gives another arc x that has the same cos value (1/2):

x = - 60 deg, or x = 360 - 60 = 300 deg

Answers within period `(0, 2pi)`: 60 deg and 300 deg