MCQ
$\cos ^4 A-\sin ^4 A$ is equal to
- A$2 \cos ^2 A+1$
- ✓$2 \cos ^2 A-1$
- C$2 \sin ^2 A-1$
- D$2 \sin ^2 A+1$
✓
Answer
Correct option: B.
$2 \cos ^2 A-1$
B
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