若asecα-2tanα=1,bsecα+tanα=2则a^2+b^2=
问题描述:
若asecα-2tanα=1,bsecα+tanα=2则a^2+b^2=
答
a*secα=1+2tanαa=cosα+2sinαb*secα=2-tanαb=2cosα-sinαa^2+b^2=(cosα)^2+4cosα*sinα+4(sinα)^2+4(cosα)^2-4cosα*sinα+(sinα)^2==[(cosα)^2+(sinα)^2]+4[(sinα)^2+(cosα)^2]+4[cosα*sinα-cosα...