(1+sinx)/cosx = -1/2
find the value of
cosx / (sinx-1)
MATHS~~~~~~
2012-06-23 9:57 pm
回答 (2)
2012-06-23 10:02 pm
✔ 最佳答案
(1 + sinx) / cosx = - 1/2(1 + sinx)cosx / cos²x = - 1/2(1 + sinx)cosx / (1 - sin²x) = - 1/2(1 + sinx)cosx / [(1 - sinx)(1 + sinx)] = - 1/2cosx / (1 - sinx) = - 1/2cosx / (sinx -1) = 1/2
2012-06-23 10:04 pm
因為 (1 + sinx) / cosx = cosx / (1 - sinx), 所以
(1 + sinx) / cosx = -1/2
==> cosx / (1 - sinx) = -1/2
==> cosx / (sinx - 1) = 1/2
(1 + sinx) / cosx = -1/2
==> cosx / (1 - sinx) = -1/2
==> cosx / (sinx - 1) = 1/2
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