Question

Find the reference angle for a rotation of 129º.

Answer 1

In order to find a reference angle, we need to find the smallest possible angle formed between the x-axis and the terminal line of the given angle, going either clockwise or counterclockwise.

Since the given angle is 129°, and 90<129<180, it will look something like this:

As we can see, the reference angle will be

`180-129=51`

so it will be 51°.