cot x + 2 csc x = 3
Find x, in degree. [0,360)
Urgent! Trigonometry
2013-10-26 8:04 pm
回答 (1)
2013-10-26 8:43 pm
✔ 最佳答案
cot x + 2 csc x = 3cosx/sinx + 2/sinx = 3
cosx + 2 = 3sinx
(cosx + 2)² = (3sinx)²
cos²x + 4cosx + 4 = 9sin²x
cos²x + 4cosx + 4 = 9(1-cos²x)
10cos²x + 4cosx -5 = 0
use -b±√(b²-4ac).....
cosx = 0.53 or -0.9348
x = 57.99⁰ or 159.2⁰
收錄日期: 2021-04-21 23:00:57
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