Basic geometry for calculations in a conical disk approximation (not to scale). Edge-on (top) and face-on (bottom) views. Two arbitrary points at the conical disk surface are marked. Two corresponding coordinate systems (x, y, ɀ) for each point are shown. They define the chosen spherical coordinate systems (r′, ϕ, θ) centered on each of these points. The distance R(φ) is defined by Eq. (D.3). The maximum conical disk height, H_τ, corresponds to the shading radius r_τ at τ_r,R = 1. M₁ and M₂ are the donor and the accretor masses. The binary separation is a.