WBBSEClass XMathematicsTrigonometric Ratio of Complementary Angle02 Mark2025 Easy

QQuestion

If sin (θ + 30°) = cos 15°, then find the value of cos 2θ.

Exam-ready answer • 02 Mark

Answer

sin (θ + 30°) = cos 15°

or, sin (θ + 30°) = sin 75°.

or, θ + 30° = 75°

or, θ = 45°.

Then, cos 2θ = cos 90° = 0.

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