3cos^2x-5sinx-1=0
Solve x
Maths 問題~~~?
2015-08-27 7:37 am
回答 (2)
2015-08-27 8:34 am
✔ 最佳答案
3cos^2x-5sinx-1=0 3(1-sin^2 x)-5sinx-1=0
-sin^2 x-5sin x-4=0
sinx=-1 or sinx=-4 (Delete)
x=270
2015-08-28 2:58 pm
3(1-sin^2 x)-5 sinx - 1 = 0
3-3 sin^2 x - 5 sinx - 1 = 0
-3 sin^2 x - 5 sinx +2 =0
sin x = -2 (rej) or sin x = 1/3
so , x = 19.5 or 161
3-3 sin^2 x - 5 sinx - 1 = 0
-3 sin^2 x - 5 sinx +2 =0
sin x = -2 (rej) or sin x = 1/3
so , x = 19.5 or 161
收錄日期: 2021-04-18 00:07:29
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