Question

How do you find the values of `theta` given `costheta=1/2`?

Answer 1

`pi/3; (5pi)/3`

Explanation:

`cos theta = 1/2`
Trigonometric table of special arcs gives -->
`theta = pi/3 (or 60^@)`
Unit circle gives another arc `theta` that has the same cos value `(1/2)`:
`theta = - pi/3` , or `theta = (5pi)/3` (co-terminal).
Answers for `(0, 2pi)`
`pi/3; (5pi)/3`