2016 AIME I Problems/Problem 4
Problem
A right prism with height has bases that are regular hexagons with sides of length 12. A vertex of the prism and its three adjacent vertices are the vertices of a triangular pyramid. The dihedral angle (the angle between the two planes) formed by the face of the pyramid that lies in a base of the prism and the face of the pyramid that does not contain measures degrees. Find .