Problems(1)
Let ABC be a triangle, and M the midpoint of the side BC. Let E and F be points on the sides AC and AB, respectively, so that ME=MF. Let D be the second intersection of the circumcircle of MEF and the side BC. Consider the lines ℓD, ℓE and ℓF through D,E and F, respectively, such that ℓD⊥BC, ℓE⊥AC and ℓF⊥AB. Show that ℓD,ℓE and ℓF are concurrent. geometry