Find the Reference Angle -120

Problem

−120^∘

Solution

1. Find a coterminal angle between 0^∘ and 360^∘ by adding 360^∘ to the given angle.

−120^∘+360^∘=240^∘

2. Identify the quadrant where the angle 240^∘ terminates. Since 180^∘<240^∘<270^∘ the angle is in Quadrant III.

3. Apply the reference angle formula for Quadrant III, which is θ^′=θ−180^∘

θ^′=240^∘−180^∘

4. Calculate the final value.

θ^′=60^∘

Final Answer

Reference Angle of −120^∘=60^∘

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