Home Sitemap Geometry Problems All problems Incenter Visual Index 551-560 Post a comment or solution        By Antonio Gutierrez
Problem 559: Triangle, Cevian, Incenters, Angle, 90 Degrees.
Level: High School, College, Math Education

The figure shows a triangle ABC with a cevian BD. If E is the incenter of triangle ABD and F the incenter of triangle BCD, prove that the measure of angle EDF is 90 degrees.

Triangle, Cevian, Incenters


Geometry problem solving is one of the most challenging skills for students to learn. When a problem requires auxiliary construction, the difficulty of the problem increases drastically, perhaps because deciding which construction to make is an ill-structured problem. By “construction,” we mean adding geometric figures (points, lines, planes) to a problem figure that wasn’t mentioned as "given."

  Recent Additions
Geometry problems 541-550