Through points A and B two oblique lines m and n are drawn perpendicular to the line AB. On line m the point C (different from A) is taken, and on line n the point D (different from B) is taken. Given the lengths of segments AB=d and CD=l and the angle φ formed by the oblique lines m and n, calculate the radius of the surface of the sphere passing through the points A, B, C, D.
geometrysphere3D geometry