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Question
Find A, if 0° ≤ A ≤ 90° and cos2 A – cos A = 0
Solution
cos2 A – cos A = 0
`=>` cos A (cos A – 1) = 0
`=>` cos A = 0 or cos A = 1
We know cos 90° = 0 and cos 0° = 1
Hence, A = 90° or 0°
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