The reference angle for -222° is 42°.
To find the reference angle for a negative angle like -222°:
1. Add 360° to the negative angle: -222° + 360° = 138°
2. Identify the acute angle between 0° and 180° that is equivalent to 138°: 138° - 90° = 48°
3. The reference angle is the acute angle, which in this case is 42° (since it's the acute angle between 0° and 90°).
Therefore, the reference angle for -222° is 42°.