EXAMPLE 3
Find
reference angles
Find the
reference angle θ' for (a) θ =
5π
3
and (b) θ = – 130°.
SOLUTION
a.
The terminal side of θ lies in
Quadrant IV.
So, θ'
= 2π – .
5π
3
π
3
=
b.
Note that θ is coterminal
with 230°, whose terminal side lies in Quadrant III. So, θ' = 230° – 180° + 50°.