The most basic geometric shape is a triangle. Triangles can be classified as scalene, isosceles, and equilateral. Scalene triangles have no congruent sides or angles, isosceles triangles have two equal sides and two equal angles, and equilateral triangles have three equal sides and three equal angles.
The sum of the internal angles of a triangle is two right angles or 180 degrees.
In Euclidean geometry, a triangle can be classified as either acute, right, or obtuse based on the measure of its largest angle. A triangle with an acute-angled vertex is called an “acute triangle” while a triangle with a right-angled vertex is called a “right-angled triangle” and so on.