If the coordinates of a triangle ABC is A(3,1), B(5,1) and C(6,8) then find the side of the triangle which is parallel to the X-axis.
AB
The sides for the triangle ABC are AB, BC, CA.
All the points with same Y-coordinates form a line which is parallel to X-axis. Among the given points A and B have the same Y-coordinates. So line AB will be parallel to X-axis.