已知tanx=2,(1)求2/3sin^2x+1/4cos^2x的值(2)求2sin^2x-sinxcosx+cos^2x的值
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已知tanx=2,(1)求2/3sin^2x+1/4cos^2x的值(2)求2sin^2x-sinxcosx+cos^2x的值已知tanx=2,(1)求2/3sin^2x+1/4cos^2x的值(2)
已知tanx=2,(1)求2/3sin^2x+1/4cos^2x的值(2)求2sin^2x-sinxcosx+cos^2x的值
已知tanx=2,(1)求2/3sin^2x+1/4cos^2x的值(2)求2sin^2x-sinxcosx+cos^2x的值
已知tanx=2,(1)求2/3sin^2x+1/4cos^2x的值(2)求2sin^2x-sinxcosx+cos^2x的值
(1)
(2/3sin^2x+1/4cos^2x)
=(2/3sin^2x+1/4cos^2x)/1
=(2/3sin^2x+1/4cos^2x)/(sin^2x+cos^2x)
上下同除cos^2x得
=(2/3tan^2x+1/4)/(tan^2x+1)
=(2/3*4+1/4)/5
=7/12
(2)
2sin^2x-sinxcosx+cos^2x
=(2sin^2x-sinxcosx+cos^2x)/1
=(2sin^2x-sinxcosx+cos^2x)/(sin^2x+cos^2x)
上下同除cos^2x得
=(2tan^2x-tanx+1)/(tan^2x+1)
=(2*4-2+1)/5
=7/5
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