2sinx-cosx=0 求sin2x和 sin^2+sinxcosx

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2sinx-cosx=0 求sin2x和 sin^2+sinxcosx
2sinx-cosx=0 求sin2x和 sin^2+sinxcosx

2sinx-cosx=0 求sin2x和 sin^2+sinxcosx
2sinx-cosx=0 2sin x=cos x tan x=sin x / cos x =1/2
sin2x =2 sin x cos x =(2 sin x cos x ) / (sin^2 x + cos^2 x )
=2tan x /(tan^2 x +1) =4/5
sin^2 x +sin x cos x =(sin^2 x +sin x cos x) / (sin^2 x + cos^2 x )
=(tan^2 x +tan x) / (tan^2 x +1)= 3/5