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​If tan (3A) = cot (A - 22°), where 3A is an acute angle, then what is the value of A?​
Question

If tan (3A) = cot (A - 22°), where 3A is an acute angle, then what is the value of A?

A.

25°

B.

27°

C.

28°

D.

30°

Correct option is C

Given:

tan(3A) = cot(A - 22°), where 3A is an acute angle,

Solution:

cot(x) = tan(90° - x).

tan(3A) = tan(90°−(A−22°))

tan(3A) = tan(90°−A+22°)

tan(3A) = tan(112°−A)

Since the tangent function is periodic with a period of 180°, we have:

3A=112°−A+n180°

where is an integer. Since 3A is an acute angle, (i.e. (0  < A < 90).

3A = 112- A

4A = 112

A = 28

∴ The correct answer is 28.

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