Question

How do you find the two quadrants that `theta` could terminate given `costheta=-0.45`?

Answer 1

`+- 93^@`

Explanation:

cos t = - 0.45
Calculator and unit circle give:
`t = +- 93^@`
Answers for `(0, 2pi)`
`93^@, 273^@` (co-terminal to `- 93^@`)