- Parallelograms on the same base and between the same parallels are equal in area.
- Parallelograms between the same parallels and having equal bases are equal in area.
- Area of a parallelogram is equal to that of a rectangle of the same base and of same altitude.
- Area of parallelogram = base x height
- The area of a triangle is half that of a parallelogram with the same base and between the same parallels.
Hence area of the triangle 
- Triangles on the same base and between the same parallels have equal areas.
- Triangles with equal areas and on the same base have equal corresponding altitudes.
