## 1. Summary

Figures that lie between two parallel lines such that their bases are common and lie on one of the parallel lines, and the vertices opposite to the base lie on the other parallel line, are said to be figures on the same base and between the same parallels. Parallelograms on the same base and between the same parallels are equal in area. The area of a triangle is equal to half the area of a parallelogram, if they are on the same base and are between the same parallels.