Answer: 1.
- A 1/2
- B 1
- C 2
- D √3/2
Correct answer: B. 1
Explanation: By the identity, sin²θ + cos²θ = 1 for ALL angles, including 30°.
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