Three-dimensional geometry in mathematics cannot be based on one's own spatial imagination. Sometimes what you think is actually wrong. Mathematics is a rigorous science, and every step of derivation must be supported by theory. Sketch in art pays attention to the perfect expression of the three-dimensional world on two-dimensional paper, which can make the viewer reproduce the three-dimensional sense. For example, the most important skill in sketching should be the so-called perspective. If you master it well, you can naturally feel the truth, but in the solid geometry of mathematics, it is impossible for such a thing to happen, and two parallel lines will not intersect at the vanishing point. In a word, mathematics is rational and art is emotional, but they actually promote each other. When I was a child, I studied sketching. It was relatively easy to learn solid geometry, and spatial imagination was still helpful.