sinA/(1+cosA)怎么化成tan(A/2)?

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sinA/(1+cosA)怎么化成tan(A/2)?

sinA/(1+cosA)怎么化成tan(A/2)?
sinA/(1+cosA)怎么化成tan(A/2)?

sinA/(1+cosA)怎么化成tan(A/2)?
sinA/(1+cosA)
=2sin(A/2)cos(A/2)/[1+2cos(A/2)^2-1]
=2sin(A/2)cos(A/2)/[2cos(A/2)^2]
=sin(A/2)/cos(A/2)
=tan(A/2)

sinA/(1+cosA)
=2sin(A/2)cos(A/2)/(1+2cos^2(A/2)-1)
=2sin(A/2)cos(A/2)/2cos^2(A/2)
=sin(A/2)/cos(A/2)
=tan(A/2)