2
Problems(2)
inverse of isosceles criterion? external angle bisectors, circumcircle related
Source: 2008 Oral Moscow Geometry Olympiad grades 8-9 p2
10/13/2020
In a certain triangle, the bisectors of the two interior angles were extended to the intersection with the circumscribed circle and two equal chords were obtained. Is it true that the triangle is isosceles?
geometryangle bisectorcircumcircleisosceles
area between 4 common tangents of 2 circles, internal are perpendicular
Source: 2008 Oral Moscow Geometry Olympiad grades 10-11 p2
10/14/2020
The radii and of two non-intersecting circles are given. The common internal tangents of these circles are perpendicular. Find the area of the triangle bounded by these tangents, as well as the common external tangents.
geometrycommon tangentsarea