Answer: sin 90° = 1.
- A sin 90° = 1
- B sin 30° + sin 60°
- C 0
- D √3/2
Correct answer: A. sin 90° = 1
Explanation: sin(30°+60°) = sin 90° = 1. Also verified by formula: sin30°cos60° + cos30°sin60° = 1/4 + 3/4 = 1.
Unit circle with standard angles 0, 30, 45, 60, 90 degrees; at 45 degrees the point is (cos45, sin45) = (1/sqrt2, 1/sqrt2).
Concept context
Ratios, identities, and applications in triangles