BY JOINING THE VETICES AND DIVIDING THE QUADRILATERAL INTO TWO
TRIANGLES.
TRIANGLES.
How Do Diagonals Of Quadrilaterals Make Triangles?
If you want to draw a line segment from a vertex to a non-adjacent vertex of a quadrilateral, there is only one choice. That one choice makes the line you draw become the third side of two different 3-sided figures (triangles). How? By creating a geometry that meets the definition of a triangle.
