1.given that sinx+cosx=4/5, sinxcosx=-9/50 and sin2x=-9/25
find the value of sin2x-cos2x
2.given that sin3x=3sinx-4sin^3 x and cos3x=4cos^2 x-3cosx
prove that cos^3 2x is identical to (cos^3 x)(cos3x)+(sin^3 x)(sin3x)
trigonometric functions m2
2011-03-12 5:34 pm
回答 (1)
2011-03-12 6:43 pm
收錄日期: 2021-04-23 23:23:51
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110312000051KK00240