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**Day seven : Ratio in a Circle**

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by Nami Youn

**Objective**

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To discover the relationship of ratio of two chords in a circle

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To understand the conditions for four points on a cirlcs

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**1. The relationship of the ratio
of two chords in a circle**

**Property : If two lines
through a point P meet a circle at points A, A' and B, B', respectively,**

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then, (PA)(PA') = (PB)(PB')**

__case 1 P is outside a circle__

gsp file

__case 2 P is inside a circle__

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