1. Classifying Triangles Lesson 15.3

2. Classifying by Angle Acute triangles have three acute angles. Obtuse triangles have one obtuse angle. Right triangles have one right angle.

3. Classifying by Sides Equilateral triangles have three congruent sides. Isosceles triangles have two congruent sides. Scalene triangles have zero congruent sides.

4. Finding Missing Angles The three angles of a triangle always add to 180°. Use a variable to stand for the missing angle and set an equation equal to 180. x + 49 + 47 = 180 x + 96 = 180 – 96 = -96 x = 84

5. Practice Time!