2017 · Q65
What is (cos⁴A - sin⁴A)/(cos²A - sin²A) equal to ?
Elementary MathematicsTrigonometry
- Acos²A - sin²A
- Bcos A - sin A
- C1
- D2
Explanation
(cos⁴A − sin⁴A) = (cos²A − sin²A)(cos²A + sin²A) = (cos²A − sin²A)·1. Cancelling the common factor leaves 1: option C.