Basic Elements of a Triangle
Mark 3 points A, B, C on a paper, such that they do not lie on a straight line. Join the line segments AB, BC and CA.
This forms a triangle ABC represented as Δ ABC or Δ BCA or Δ CAB.
In Δ ABC, the line segments AB, BC and CA are called the sides of the triangle and ∠ CAB, ∠ABC and ∠BCA (∠A, ∠B & ∠C) are called the angles of the triangle. The point of intersection of two sides of the triangle is called the vertex. A, B and C are three vertices of ∆ ABC. Hence, a triangle has 3 sides, 3 angles and 3 vertices.
Can a triangle be drawn using 3 points on a straight line