Question

What is `cos^-1(1/2)`?

Answer 1

`=60`

Explanation:

`cos^-1(1/2)`
`=60`

Answer 2

`pi/3, and (5pi)/3`

Explanation:

`arccos x = 1/2`
Trig table of special arcs gives
`cos x = 1/2` --> `x = pi/3`
Trig unit circle gives another arc x that has the same cos value -->
`cos x = 1/2` --> `x = - pi/3`, or, `x = (5pi)/3` (co-terminal)
Answers: `pi/3 and (5pi)/3`