Master Xia Jin! "Superclass" knowledge commonly used in mathematics problems at the end of senior high school entrance examination

The distance formula between two points of coordinate axis, the distance from any point to a straight line, the parallelism and verticality of two straight lines, and the projective theorem. Cutting line theorem. Secant theorem and proportional theorem of equal sides of straight lines in angular plane. Vieta theorem. Arithmetic progression's general formula and summation formula. General formula of geometric series. Closed fraction theorem. Equal ratio theorem. Heron's formula