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Trigonometry on the Unit Circle

This test explores angles of any magnitude and direction and their representation on the unit circle. Tasks cover coterminal-angle reduction, periodicity and the use of inverse trigonometric functions.

Questions: 10Estimated time: 10 minutes
Trigonometry on the Unit Circle
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Sample questions

  1. Calculate sin ___°.
  2. Simplify sin(−___°).
  3. Simplify sin(___° + 360° · ___).
  4. Simplify tan(___° + 180° · ___).
  5. Calculate arcsin(___).

Rotation-angle trigonometry

A rotation angle is measured from the positive x-axis: anticlockwise angles are positive and clockwise angles negative. On the unit circle, the point has coordinates (cos α, sin α), and periodicity permits replacement by a coterminal angle.

Quadrants and radians

Quadrants determine the signs of sine and cosine, while tangent is positive in quadrants I and III. Use 180° = π radians for conversion. A reference angle gives the magnitude of a trigonometric value, but its sign must still be selected from the quadrant.

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