tana=2则sina方+sinacosa=

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tana=2则sina方+sinacosa=
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tana=2则sina方+sinacosa=
tana=2则sina方+sinacosa=

tana=2则sina方+sinacosa=
sina方+sinacosa
=(sina方+sinacosa)/(sin²a+cos²a)
=(tan²a+tana)/(1+tan²a) (上下同时除以cos²a)
=(4+2)/(1+4)
=6/5

sina^2+sinacosa=sina^2/(sina^2+cosa^2)+sinacosa/(sina^2+cosa^2)
sina^2/(sina^2+cosa^2)=1/(1+1/tana^2)=4/5
sinacosa/(sina^2+cosa^2)=1/(tana+1/tana)=2/5
sina^2+sinacosa=6/5