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2 cos x=sin x + 1,find x
發問:
2 cos x=sin x + 1,find x
最佳解答:
Taking square on both sides: 4(cos x)2 = (sin x)2 + 2 sin x +1 4﹣4(sin2x) = (sin2x) + 2 sin x +1 5 (sin2x) + 2 sin x﹣3 = 0 (5 sin x﹣3) (sin x + 1) = 0 sin x = 3/5 or sinx = -1(rejected, x = 270 deg) x = 36.97°or x = 143.13°(rejected, checked by input back to formula) Hence,x = 36.97°
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