Question

What are the exact values of cos 150° and sin 150°?

Answer 1

`cos(150) = -sqrt(3)/2`
`sin(150) = 1/2`

Explanation:

First of all, observe that `150=180-30`.

Then, remember that we have

`cos(180-x) = -cos(x)`
`sin(180-x) = sin(x)`

Plug in `x=30` to get

`cos(180-30) = -cos(30)`
`sin(180-30) = sin(30)`

the answer comes from the fact that `cos(30)=sqrt(3)/2` and `sin(30)=1/2` are known values.