Answer: 2.
- A 1
- B 2
- C 3
- D 4
Correct answer: B. 2
Explanation: Rearranging gives 2sin²x + sinx − 1 = 0, so sinx = 1/2 or sinx = −1. sinx = −1 makes secx undefined, leaving x = π/6, 5π/6: 2 solutions.
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