tag:blogger.com,1999:blog-6933544261975483399.post5293927745702859564..comments2024-03-26T19:10:02.918-07:00Comments on Go Geometry (Problem Solutions): Problem 720: Excenter, Intersecting Circles, Angle, MeasurementAntonio Gutierrezhttp://www.blogger.com/profile/04521650748152459860noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-6933544261975483399.post-79925178288261353392012-01-23T18:38:21.715-08:002012-01-23T18:38:21.715-08:00Let CO'D cut the circle (O') at E.
By the ...Let CO'D cut the circle (O') at E.<br />By the result of Problem 719,<br />E is the incentre of ∆ABC<br />Observing that ED is a diameter of circle (O'),<br />it follows that AD ⊥ AE, implying that<br />AD is the external bisector of ∠CAB. <br />By symmetry,<br />BD is the exteral bisector of ∠CBA.<br />Hence D is an excentre of ∆ABCPravinhttps://www.blogger.com/profile/05947303919973968861noreply@blogger.com