A triangle is a polygon with three sides and three vertices. It is one of the most basic shapes in geometry. Every triangle has three corners called vertices, three straight sides connecting these vertices, and three interior angles.
Triangles can be classified in different ways. By their sides, we have three types: equilateral triangles have all three sides equal, isosceles triangles have two sides equal, and scalene triangles have all sides different lengths.
Triangles can also be classified by their angles. An acute triangle has all angles less than ninety degrees. A right triangle has exactly one angle equal to ninety degrees. An obtuse triangle has one angle greater than ninety degrees.
Triangles have several important properties. The sum of all three interior angles always equals one hundred eighty degrees. The triangle inequality states that the sum of any two sides must be greater than the third side. The area of a triangle can be calculated using the formula: one half times base times height.
To summarize what we have learned about triangles: A triangle is a fundamental polygon with three sides and three vertices. We can classify triangles by their sides or angles, and they have important properties like the angle sum being one hundred eighty degrees.