all internal angles are less than diagonals lie 180

To clarify, it seems like you're describing a property of polygons, specifically that all internal angles are less than 180 degrees, and the diagonals lie within the plane of the polygon. However, this statement is not entirely clear. Let's break it down: 1. **All internal angles are less than 180 degrees**: This is true for all polygons except for the triangle, which has internal angles that sum to exactly 180 degrees. For any polygon with more than three sides, each internal angle is less than 180 degrees. 2. **Diagonals lie within the plane of the polygon**: This is true for all polygons. A diagonal is a line segment connecting two non-adjacent vertices of a polygon, and it always lies within the plane of the polygon. If you're looking for a specific problem related to these properties, please provide more details, and I'll be happy to help you solve it.