已知tana=2,则sin^2a +sinacosa/sin^2+1的值

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已知tana=2,则sin^2a+sinacosa/sin^2+1的值已知tana=2,则sin^2a+sinacosa/sin^2+1的值已知tana=2,则sin^2a+sinacosa/sin^

已知tana=2,则sin^2a +sinacosa/sin^2+1的值
已知tana=2,则sin^2a +sinacosa/sin^2+1的值

已知tana=2,则sin^2a +sinacosa/sin^2+1的值
sin^2a +sinacosa/sin^2+1?是sin^2a +sinacosa/sin^2a+1吧?
sin^2a +sinacosa/sin^2a+1
=sin^2a +sinacosa/(2sin^2a+cos^2a) (因为1=sin^2a+cos^2a)
=tan^2a+tana/2tan^2a+1 (分子,分母同除以cos^2a)
=6/9=2/3