tanx=1/2,sin2x+sin^2x

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tanx=1/2,sin2x+sin^2x

tanx=1/2,sin2x+sin^2x
tanx=1/2,sin2x+sin^2x

tanx=1/2,sin2x+sin^2x

tanx=1/2 即:

sinx/cosx=1/2, 所以,

2sinx=cosx

sin2x=(2sinx)cosx=cos^2x

sin2x+sin^2x=cos^2x+sin^2x=1

解sin2x+sin^2x
=(2sinxcosx+sinxsinx)
=(2sinxcosx+sinxsinx)/1
=(2sinxcosx+sinxsinx)/(cos^2x+sin^2x) (分子分母同时除以cos^2x)
=(2tanx+tan^2x)/(1+tan^2x)
=[2×1/2+(1/2)^2]/(1+(1/2)^2]
=[1+(1/4)]/(1+1/4)
=5/5
=1