Answer: -sin 15°.
- A sin 15°
- B -sin 15°
- C cos 15°
- D -cos 15°
Correct answer: B. -sin 15°
Explanation: 195° = 180° + 15°. sin(180°+θ) = -sinθ. So sin 195° = -sin 15°.
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