若tanα =3,求2sinα-3cosα/4cosα+5sinα+3sin^2α-4cos^2α

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若tanα =3,求2sinα-3cosα/4cosα+5sinα+3sin^2α-4cos^2α
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若tanα =3,求2sinα-3cosα/4cosα+5sinα+3sin^2α-4cos^2α
若tanα =3,求2sinα-3cosα/4cosα+5sinα+3sin^2α-4cos^2α

若tanα =3,求2sinα-3cosα/4cosα+5sinα+3sin^2α-4cos^2α
tanα=3=sinα/cosα
(sinα)^2+(cosα)^2=1
sinα =3/√10
cosα =1/√10
cos2α =cosα^2-sinα^2=-8/10
sin2α=2sinαcosα=6/10
即可得到相关结果