3.6 Types of Triangles Objective: After studying this lesson you will be able to name the various types of triangles and their parts.

Definition:. a scalene triangle is a triangle in which no Definition: a scalene triangle is a triangle in which no two sides are congruent. Definition: an isosceles triangle is a triangle in which two sides are congruent. C A B In triangle ABC, BC is the called the base, angles B and C are called base angles. Angle A is called the vertex angle.

Definition:. an equilateral triangle is a triangle in which Definition: an equilateral triangle is a triangle in which all sides are congruent. Definition: an equiangular triangle is a triangle in which all angles are congruent.

Definition:. an acute triangle is a triangle in which all Definition: an acute triangle is a triangle in which all angles are acute. 80 60 40 Definition: a right triangle is a triangle in which one of the angles is a right angle. The side opposite the right angle is called the hypotenuse. The sides that form the right angle are called the legs. hypotenuse leg leg

Definition:. an obtuse triangle is a triangle in which one Definition: an obtuse triangle is a triangle in which one angle is obtuse. 112 32 36 Given: Prove: A 70 B C D

F G E H Given: Prove:

Given: Prove: Reason Statement J O P K M 1 3 2 4 1. 2. 3. 4. 5. 6. 7. 8. 9. 1. 2. 3. 4. 5. 6. 7. 8. 9.

Summary: Name the different types of triangles and their characteristics by which we classify them? Homework: worksheet