2018 · Q61
If cos x + cos²x = 1, then what is sin²x + sin⁴x equal to?
Elementary MathematicsTrigonometry
- A1
- B1.5
- C2
- D3
Explanation
From cos x = 1 − cos²x = sin²x, substitute into sin²x + sin⁴x to get cos x + cos²x, which equals 1 by the given condition, option (A).