InterviewSolution
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InterviewSolution
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7 sin^[email\xa0protected] + 3 cos^[email\xa0protected] = 4 , then prove [email\xa0protected] = 1/√3 |
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Answer» Nice ?? 7 sin²A + 3 cos²A = 4=> 4 sin²A + 3 sin²A + 3 cos²A = 4=> 3 sin²A + 3 cos²A = 4 - 4 sin²A=> 3( sin²A + cos²A ) = 4( 1 - sin²A )=> 3( 1 ) = 4( cos²A )=> 3 = 4 × cos²A = CosA=√3/2 => cosA=cos30° = > A=30° |
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