Problems(1)
The incircle of triangle ABC tangents BC, CA, AB at D, E, F, respectively. Let the tangents of E, F with respect to ā(AEF) intersect at P, and X be a point on BC such that EF, DP, AX are concurrent. Define Q, Y and R, Z similarly. Show that X, Y, Z are collinear. geometryincircletangent