Detailed description
Circle with radius of 1, centre of circle at origin O. Point marked on circle in quadrant 1 as (cos 30 degrees, sin 30 degrees). Point marked as P(cos 210 degrees, sin 210 degrees) in quadrant 3. Right-angled in first quadrant and congruent triangle POQ in the third quadrant with angle POQ = 30 degrees. Angle of 210 degrees marked.
