Geometric Properties of Triangles. A triangle is aptly named: it is composed of three (tri) angles formed by three non-coincident, non-parallel lines. That the lines are non-coincident means they do not overlap, and that they are non-parallel means that each line intersects with every other line.

What are examples of intersecting lines?

Crossroads: Two roads (consider as straight lines) meeting at a common point make crossroads. Scissors: The two arms of the scissors form intersecting lines.

What kind of lines does a triangle have?

A triangle is a shape formed when three straight lines meet. All triangles have three sides and three corners (angles).