1, there are all kinds of three-dimensional figures in life, and the common geometric bodies are cylinders, cones, cubes, cuboids, prisms, pyramids, spheres and so on. 2. Any geometry is composed of points, lines and faces. Points have no size, lines have straightness but no thickness, planes extend indefinitely, faces have planes and faces, and lines intersect. Points become lines, lines become faces, and faces become bodies. Points, lines, faces and bodies are all geometric figures. 3. Definition of prism: (1) edge: In a prism, the intersection of any two adjacent faces is called a side, and all sides of the prism are equal in length. (2) Surface: The upper and lower bottom surfaces of the prism are the same. The sides are all rectangles, and the name of the prism is related to the number of sides of the bottom polygon. 4. Whether a figure can become a prism after folding depends on whether there are two bottom faces, the shape of the bottom face and the position of the two bottom faces. Learn to sum up the rules by yourself. When the surface of a cube is cut along some edges, more than ten different plane figures can be obtained, which can be folded into a cube. The side development diagrams of cylinder and cone are rectangular and fan-shaped respectively. Three-dimensional graphics expand and collapse plane graphics. Cutting the surface of any three-dimensional figure along some edges can get different plane figures, so you must improve your spatial imagination. 7. Cut a cube with a plane. If this plane intersects with several faces of this cube, the cross section is just a few polygons, and triangles, quadrangles, pentagons and hexagons can be obtained in turn, but heptagons cannot be obtained. 8. Use the plane to cut the geometry. Different positions of plane cross-section will produce different cross-sections. Common cross sections are polygons or circles. 9. The picture from the front is called the front view, the picture from the left is called the left view, and the picture from above is called the top view. 10, learn to draw three views. According to the top view of the geometry built by several small cubes, know the front view and left view of the geometry, and build the geometry according to the front view and top view. Pay attention to observation when solving problems and determine the number of columns in the front view \ left view. When determining the height of each column. 1 1, the graphics in life cannot be separated from polygons. It is a closed figure composed of line segments that are not on the same line, thus forming n sides.