Answer: 0.
- A 0
- B 1
- C 1/2
- D √3/2
Correct answer: A. 0
Explanation: cos 90° = 0. At 90 degrees, the adjacent side is zero.
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