evaluate the following expressions.
1.sin2x+cos2x when tanx=-2
2.(sinx+cosx)^2 when tanx=1/3
show it step by step thx
given tanx=2t/(1-t^2) cosx = (1-t^2)/(1+t^2) sinx=2t/(1+t^2) where t=tan(x/2)?
2015-04-12 3:34 am
回答 (1)
2015-04-12 4:03 am
✔ 最佳答案
1/sin(2x) = 2(-2) / (1+(-2)^2) = -4/5
cos(2x) = (1-4)/(5) = -3/5
--->answer = -7/5
2/
(sinx+cosx)^2 = 1 + sin(2x) =1 +(2/3)/(1+(1/3)^2) = 1 3/5
收錄日期: 2021-05-01 15:20:05
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20150411193434AA3WW0Y