If I have r as an inradius of a triangle and ra, rb, rc are the three radii of the 3 excircles of that triangle how can I show that:

1/ra+1/rb+1/rc=1/r?

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- March 2nd 2010, 05:39 AM #1

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- March 2nd 2010, 06:24 AM #2

- March 2nd 2010, 09:20 AM #3

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- March 2nd 2010, 10:03 AM #4