maths~
2008-06-19 5:31 am
回答 (1)
2008-06-19 7:27 am
✔ 最佳答案
OB = OC = radiustriangle OBC is an isosceles triangle
angle OBC = angle OCB = 180 - 120 = 60
angle BOC = 180 - angle OBC - angle OBC = 180 - 60 - 60 = 60
angle BAC = 0.5 x angle BOC = 0.5 x 60 = 30
(angle at circumference = 0.5 times of angle at centre)
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原文連結 [永久失效]:
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