Rectangular, square, triangle, parallelogram. Plane figure is a kind of geometric figure. According to the guide, there are rectangles, squares, triangles and parallelograms. A plane figure is a figure with all points on the same plane. Plane means that all the connecting lines of any two points on a surface fall on this surface, which is a two-dimensional zero curvature continuation. Such a surface is a straight line and intersects with any similar surface.