Question

How do you find the value of `sin (-120)`?

Answer 1

`sin(-120^@) = -sqrt(3)/2`

Explanation:

`120^@` is equivalent to a reference angle of `60^@` in Quadrant III

`sin(60^@) = sqrt(3)/2`
but in Quandrant III the `sin` is negative (using CAST notation)

so `sin(-120^@) = -sqrt(3)/2`