Strict solid geometry is similar to geometric drawing. Generally, given a three-dimensional figure and three fixed points, a section polygon is made by strict geometric method.

(1) Two points determine a straight line.

(2) Only two straight lines on the same plane will intersect, and the intersection point is the actual intersection point.

(3) If it is known that two non-overlapping planes have a common point, the intersection of the two planes must pass through the common point.

Plane and solid

The earliest geometry belongs to plane geometry. Plane geometry is to study the geometric structure and measurement properties (area, length, angle) of straight lines and quadratic curves (that is, conic curves, that is, ellipses, hyperbolas and parabolas) on the plane. Plane geometry adopts axiomatic method, which is of great significance in the history of mathematical thought.

The content of plane geometry naturally transferred to solid geometry of three-dimensional space. In order to calculate the problem of volume and area, people have actually started to involve the original concept of calculus.