Supplementary Investigation 4

Another Ratio

Tool(s) Geometers Sketchpad

Data File(s) si4

Focus This activity provides a different analysis of the manner by which two orthogonal circles divide the interior portions of a secant passing through the center of one of the circles.

Tasks

1. Using the arrow icon, move the drag pts and observe the effect on the ratios of distances displayed. State a conjecture based on your observations. To prove your conjecture false, what sort of counter example would be necessary?

2. Show that the cross ratio is equal to r/(r-1).

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