Triangles are often classified by either their number of sides or the measures of their angles. If all the lengths of their sides are different it is scalene. If the length of two sides of the triangle are equal it is called isosceles. If two sides of a triangle are congruent that are considered the same in all respects. The Isosceles Triangle Theorem tells us that if you have an isosceles triangle the angles opposite the congruent sides are also congruent. If all sides are equal it is called equilateral. When it comes to angles of triangles: acute (all angles are acute), right (one right angle), obtuse (one obtuse angle), and equiangulars (you guessed it; have all equal angles).

What Are Equilateral and Isosceles Triangles? Isosceles - Suppose two sides of a triangle are congruent, the angles that are opposite are congruent. The congruent sides are called legs from the vertex angle, and the other two are base angles. These isosceles shapes are used in regular polygon areas plus, the triangles are called 45-45-90. You can find the other two isosceles triangles if you have one interior angle. The examples of the isosceles are the golden triangle, isosceles right triangles, and the faces of bipyramids as well as certain Catalan solids. Equilateral - This is a triangle that has all three sides equal or of the same length. The Equilateral has a property with all three interior angles. It is a specific case of a regular polygon, but here, with three sides. You may construct an equilateral triangle of a provided side length using a straightedge and a compass. The radius of an equilateral is half the radius of a circumcircle. All three angles are always 60 degrees. These worksheets explain how to identify these types of triangles. Students will calculate angles and side lengths of each triangle, match definitions containing angle degrees, and more.