Some relations between the orthic and the median triangles

Extract

Let ABC be the triangle, X, Y, Z the feet of the altitudes, H the orthocentre, A′,B′,C′ the mid points of the sides.

Let ZY meet A′B′ in D, A′C′ in D′, B′C′ in R:

ZX meet B′C′ in E, A′B′ in E′, A′C′ in S:

XY meet C′A′ in F, B′C′ in F′, A′B′ in T.