**Category:** Geometry  
**Subtype:** Solid Geometry (Prisms)  
**Problem Description:** The problem involves a right prism and requires finding the angle between two planes: one defined by points \(A\), \(M\), and \(N\) and the other defined by points \(A\), \(B\), and \(C\). Specifically, it asks for the measure of the angle between these two planes.