Question

How do you find the exact value of `cos^-1(-1)`?

Answer 1

`(2n+-1)pi` where `ninZZ`

Explanation:

Assume,
`=>cos^-1(-1)=theta`
`=>costheta=-1`
`=>costheta=cospi`
`=>theta=2npi+-pi` where, `ninZZ`
`=>theta=(2n+-1)pi` ; `ninZZ`