How do I find the reference angle for the angle measuring 21pi/4 radians?

Question

How do I find the reference angle for the angle measuring 21pi/4 radians?

Answer 1

Hello Elisa!

A good tip is to try to put the angle in the form n*2π, where n is an integer. Note that:

21π/4 = 24π/4 - 3π/4 = 3*2π - 3π/4

The reference angle is the smallest angle that the terminal side of a given angle makes with the x-axis.

The reference angle is π - 3π/4 = π/4