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If sin a = 1/2 prove that (3cos a-4coscube a) |
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Answer» SINA(1+sin^2A) = cos^2A sinA(2 -cos^2A) = cos^2A Squaring both SIDES, sin^2A(4-4cos^2A +cos^4A) = cos^4A (1-cos^2A)(4-4cos^2A +cos^4A) = cos^4A 4-4cos^2A +cos^4A-4cos^2A+4cos^4A-cos^6A = cos^4A 4 -cos^6A +4cos^4A -8cos^2A = 0 cos^6A - 4 cos^4A + 8cos^2A = 4 Hence PROVED. |
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