Question

How do you use a calculator to evaluate `sin(-0.65)`?

Answer 1

`-40^@54, 220^@54`

Explanation:

sin x = - 0.65
Calculator gives -> - 0.65 --> 2nd --> sin -->
x = - 40^@54
Unit circle gives another x that has the same sin value:
`x = 180 - (-40.54) = 220^@54`