Pre-Calculus 12 · Geometry
The Unit Circle and Radian Measure
A radian is the angle subtended by an arc equal in length to the radius — a definition that makes the unit circle the natural home for trigonometry. Students memorize the unit circle's key coordinates (for 30°, 45°, 60° and their equivalents in radians), giving them exact values that will be needed in every subsequent trigonometry unit.
WHAT STUDENTS WILL LEARN
✓Define radian measure and convert between radians and degrees
✓Identify coordinates on the unit circle for standard angles
✓Determine exact values of sine, cosine, and tangent for special angles
✓Extend trigonometric ratios beyond the first quadrant using CAST
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