The base of the pyramid is a triangle ABC, in which ∠ACB=30o, and the length of the median from the vertex B is twice less than the side AC and is equal to α . All side edges of the pyramid are inclined to the plane of the base at an angle a. Determine the cross-sectional area of the pyramid with a plane passing through the vertex B parallel to the edge AD and inclined to the plane of the base at an angle of β, geometry3D geometrypyramid