Find the measure of the reference angle for a 170° angle.

To find the reference angle for a 170° angle, follow these steps:

1. Understand that the reference angle is always the acute angle (less than 90°) that the terminal side of the given angle makes with the x-axis.

2. For an angle of 170°, the terminal side is in the second quadrant.

3. The reference angle is the difference between the given angle and 180° (since 180° is the angle on the straight line or the x-axis in the second quadrant).

4. So, subtract 170° from 180°.

5. The result is 10°.

So, the reference angle for a 170° angle is 10°.