Trigonometrymedium · Past Paper

What is the simplified form of cos⁴ θ - sin⁴ θ?

A1
Bcos 2θ
Csin 2θ
Dcos² θ

✓ Correct Answer: Bcos 2θ

Factorizes to (cos² θ - sin² θ)(cos² θ + sin² θ) = cos 2θ * 1 = cos 2θ.

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