If sin(2x)=cos(x+30°), what is the value of x?
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Correct answer: B
Explanation
Given:
sin(2x) = cos(x + 30°)
Using the formula:
cosθ = sin(90° − θ)
sin(2x) = cos(x + 30°)
sin(2x) = sin[90° − (x + 30°)]
sin(2x) = sin(60° − x)
2x = 60° − x
3x = 60°
x = 20°