Answer: All are equal.
- A sec²θ + cosec²θ
- B 2 + 2tanθ + 2cotθ + tan²θ + cot²θ
- C (secθ+cosecθ)²
- D All are equal
Correct answer: D. All are equal
Explanation: Expanding LHS and RHS both give sec²θ + cosec²θ + 2secθ cosecθ. They are equal.
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