The length of one side in a triangle is less than the sum of the lengths of the other two sides; is greater than the absolute value of their differences.

In a triangle, the sides opposite equilateral angles are equal.

A triangle has a large side against a major angle and a smaller side against a small angle.

The line segment passing through the midpoints of two sides in a triangle is parallel to the third side and its length is equal to half the length of the third side.

The sum of the distances of any point in a triangle to the vertices of the triangle is greater than the half circumference of the triangle and smaller than its circumference.