已知sina/2-cosa/2=-根号5/5,求tan(2a-π/4)已知sina/2-cosa/2=-根号5/5,且450

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已知sina/2-cosa/2=-根号5/5,求tan(2a-π/4)已知sina/2-cosa/2=-根号5/5,且450已知sina/2-cosa/2=-根号5/5,求tan(2a-π/4)已知s

已知sina/2-cosa/2=-根号5/5,求tan(2a-π/4)已知sina/2-cosa/2=-根号5/5,且450
已知sina/2-cosa/2=-根号5/5,求tan(2a-π/4)
已知sina/2-cosa/2=-根号5/5,且450

已知sina/2-cosa/2=-根号5/5,求tan(2a-π/4)已知sina/2-cosa/2=-根号5/5,且450
(sina/2-cosa/2)^2=(-根号5/5)^2
sina=4/5,tana<0
tana=-4/3
tan2a=2tana/(1-tan^2a)=24/7
tan(2a-π/4)
=(tan2a-tanπ/4)/(1+tan2a*tanπ/4)
=17/31