
Problem 258.
Equilateral Triangle, Incircle, Point, Vertices,
Side, Distances, Squares 
The figure shows an
equilateral triangle ABC. If a point D is on the incircle, DA = d, DB = e, DC = f, and
AC = a, prove that
.
View or post a solution.
See also:
Median length, Apollonius' Theorem
Euclid's Elements Book II Proposition 13
Problem
257
Problem
256
Equilateral Triangle

