If sin(90°−x) = cos(2x−30°), and x is acute, find the value of x.
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Correct answer: A
Explanation
Given,
sin(90° − x) = cos(2x − 30°)
sin(90° − x) = cos x
cos x = cos(2x − 30°)
sin(90° − x) = cos(2x − 30°)
cos A = cos B
A = B or A = −B
Case 1:
x = 2x − 30°
x = 30°