prove that :
cos3θ / sinθ + sin3θ / cosθ = 2cot2θ
三角學問題 1
2007-05-11 6:11 am
回答 (1)
2007-05-11 6:23 am
✔ 最佳答案
LHS = cos3θ / sinθ + sin3θ / cosθ= (cos3θ cosθ + sin3θ sinθ)/(sinθcosθ)
= cos(3θ-θ) / 0.5sin2θ
= 2cos2θ/sin2θ
= 2cot2θ
= RHS
收錄日期: 2021-04-30 22:19:33
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070510000051KK04912