If sin (θ + 30°) = cos 15°, then find the value of cos 2θ.
WBBSE
Class X
Mathematics
Trigonometric Ratio of Complementary Angle
02 Mark
2025
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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