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標題:
急~如何計算 80 cos x + 50 sin x = 64 ?
發問:
80 cos x + 50 sin x = 64 求x 請幫幫忙！
最佳解答:
80 cos x + 50 sin x = 64 ---> 80(√(1 - (sinx)^2)) + 50 sin x = 64 (because (sin x)^2 + (cos x)^2 = 1) ---> √(1 - (sinx)^2) = (64 - 50 sin x) / 80 ---> (1 - (sinx)^2) = (64 - 50 sin x)^2 / 6400 ---> 2225 (sin x)^2 - 1600 (sin x) - 576 = 0 By solving the quadratic equation : sin x = 0.98257 or sin x = -0.26347 Therefore x = 79.28(degree) or x = -15.28(degree)
急~如何計算 80 cos x + 50 sin x = 64 ?
發問:
80 cos x + 50 sin x = 64 求x 請幫幫忙！
最佳解答:
80 cos x + 50 sin x = 64 ---> 80(√(1 - (sinx)^2)) + 50 sin x = 64 (because (sin x)^2 + (cos x)^2 = 1) ---> √(1 - (sinx)^2) = (64 - 50 sin x) / 80 ---> (1 - (sinx)^2) = (64 - 50 sin x)^2 / 6400 ---> 2225 (sin x)^2 - 1600 (sin x) - 576 = 0 By solving the quadratic equation : sin x = 0.98257 or sin x = -0.26347 Therefore x = 79.28(degree) or x = -15.28(degree)
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