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發表於 2005-4-6 21:07:56
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顯示全部樓層
1.Join line AC,Let PAB be X
Angle BAC =90
Angle PAB = Angle BCA (Angle in alt.segment)
Angle CAQ = Angle CBA (Angle in alt. segment)
Since arc BA =2 arc AC
So, BCA = 2 CBA(arcs prop. to arcs at ce)
IN Tri ABC
BAC+X+1/2X = 180
X=60
So,PAB =60 |
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