[幾何小問題]：If You Lose Your Compass

[幾何小問題]：If You Lose Your Compass

如圖，給一圓，和過圓心O的直線L，另一點P不在圓和直線L上。

請使用可以畫出直線的"工具"，作出垂直給定的直線L。

試找出作法？

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If You Lose Your Compass

Given a circle with center O, a line through O, and a point P not on the line or on the circle, construct "with unmarked straightedge only" a line through P perpendicular to the given line .
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參考解法：

設L交O於A,B
作線PA及PB，並延長使之與O有交點
PA與O交於D、PB與O交於E
作線BD及AE，並延長使之相交於F
PF 垂直 L

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文章出處： TI Education
圖片來源：TI Education (點擊圖片可連結原圖)
參考解法提供：Fed Tang  (發表於 TI Education  )