maths-circle(2)
2011-02-10 5:13 am
圖片參考：http://img819.imageshack.us/img819/1900/84725699.jpg
In the figure, PT and QT are tangents to the circle at P and Q respectively. S is a point on the circumference such that ∠PSQ=124°. Find ∠PTQ.
回答 (1)
2011-02-10 5:25 am
✔ 最佳答案
let a point O be the centre of the circlejoin OP and OQ
角OPT and 角OQT=90(tangent perpendicular radius)
reflex angle POQ=124乘2=248(angle at centre twice angle at circumference)
角POQ=360-(124乘2) =112 (angle at a point)
in quad POQT
angle PTQ=360-90-90-112=68
所以角PTQ=68
2011-02-09 21:28:19 補充：
angle PTQ=360-90-90-112=68
(angle sum of polygon)
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110209000051KK01667