sinx+cosx=1/5,求(sin2x+(2sinx)^2)/1-tanx
问题描述:
sinx+cosx=1/5,求(sin2x+(2sinx)^2)/1-tanx
-90
答
设sinX=acosX=b a^2+b^2=1----------------(1) a+b=0.2 ------------------(2)解得 a=0.8 b=-0.6 或a=-0.6 b=0.8 原试=2sinxcosx+(2sinx)^2/1-sinx/cosx =24/35