This document describes basic 2D shapes - the square, rectangle, and triangle. It notes that squares and rectangles both have four sides and four corners, but squares have all sides of equal length while rectangles have opposite sides of equal length. Triangles are defined as having three sides and three corners. A table is included that can be completed with this information about each shape's name, number of sides/corners, and other key features.

2. SQUARE CORNER CORNER CORNER CORNER SIDE SIDE SIDE SIDE

4. RECTANGLE CORNER CORNER CORNER CORNER SIDE SIDE SIDE SIDE

6. TRIANGLE CORNER CORNER CORNER SIDE SIDE SIDE