求证:tana/2=sina/1+cosa=1-cosa/sina
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![求证:tana/2=sina/1+cosa=1-cosa/sina](/uploads/image/z/1711567-55-7.jpg?t=%E6%B1%82%E8%AF%81%EF%BC%9Atana%2F2%3Dsina%2F1%2Bcosa%3D1-cosa%2Fsina)
求证:tana/2=sina/1+cosa=1-cosa/sina
求证:tana/2=sina/1+cosa=1-cosa/sina
求证:tana/2=sina/1+cosa=1-cosa/sina
tan(a/2)
=sin(a/2)/cos(a/2)
=2sin(a/2)cos(a/2)/[2cos^(a/2)]
=sina/(1+cosa)
=sina(1-cosa)/(1-cos^a)
=sia(1-cosa)/sin^a
=(1-cosa)/sina.