Answer: sec²θ.
- A sec²θ
- B cosec²θ
- C cos²θ
- D sin²θ
Correct answer: A. sec²θ
Explanation: Pythagorean identity: 1 + tan²θ = sec²θ.
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