Question

How do you find the exact value of `sec^-1(2)`?

Answer 1

`60^@, 300^@`

Explanation:

`sec^-1(2) --> arcsec (2)`
If sec = 2 --> `cos x = 1/2`
Trig table (or calculator) gives -->
`cos x = 1/2` --> arc `x = pi/3`, or 60^@
Trig unit circle gives another arc x that has the same cos value (1/2): `x = - pi/3 or 300^@`