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Question
If tan 2A = cot (A – 18°), where 2A is an acute angle, find the value of A
Solution
tan 2A = cot (A – 18°)
cot (90° – 2A) = cot (A – 18°)
(∵ cot (90° – θ) = tan θ)
90° – 2A = A – 18°
3A = 108°
A = 36°
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