A triangle is composed of three line segments. The line segments intersect in their endpoints. To name a triangle we often use its vertices (the name of the endpoints). A triangle has three angles. The sum of the measures of the angles is always 180° in a triangle. In this math lesson we are going to take a little closer look at triangles. In your packet you will find sheets of paper with your triangles. You will need to cut these out to complete the activities.