Proposed Problem

Click the figure below to see the complete problem 375 about Triangle, Excenter, External Angle Bisectors.

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Complete Geometry Problem 375

Level: High School, SAT Prep

## Tuesday, October 27, 2009

### Problem 375: Triangle, Excenter, External Angle Bisectors

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Let AB, BC, AC touch the circle at F, D, G. Since triangle AFE, BFE and CGE are congruent to AGE, BDE and CDE, alpha=angle BED+angle CED=(90-A/2)/2+(90-A/2)/2=90-A/2.

ReplyDeletealpha=360-(A+B+c+90-B/2+90-C/2)=B+C/2=90-A/2

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