A triangle has three internal angles, each one bounded by a pair of adjacent edges; the sum of angles of a triangle always equals a straight angle (180 degrees or π radians). The triangle is a plane figure and its interior is a planar region. Learn the rules and properties of triangles, such as the sum of interior angles, the triangle inequality theorem, and the relationship between sides and angles. Explore interactive demonstrations and practice problems on triangle geometry. Learn why all triangles have 180 degrees and how to measure the angles of a triangle. See examples of different types of triangles and how to classify them by their angle measurements. The interior angles of a triangle always add up to 180° while the exterior angles of a triangle are equal to the sum of the two interior angles that are not adjacent to it. Learn about the different types of triangles, how to identify their angles, and how to calculate their perimeter and area. A triangle has three sides and three angles that always add to 180°. This page explains the characteristics of triangles, which have three sides and angles summing to 180 degrees. They can be classified by side lengths into isosceles, equilateral, and scalene, and by … To what degree do the angles in a triangle add up? According to the angle sum property of a triangle, the three interior angles in a triangle add up to 180 degrees.
