Let A,B,C,D be four different points on a line ℓ, such that AB=BC=CD. In one of the semiplanes determined by the line ℓ, the points P and Q are chosen in such a way that the triangle CPQ is equilateral with its vertices named clockwise. Let M and N be two points on the plane such that the triangles MAP and NQD are equilateral (the vertices are also named clockwise). Find the measure of the angle ∠MBN. anglesequilateralsequal segmentsgeometry