1. 4-1 Classifying Triangles

2. What Is a Triangle? A triangle is a three-sided polygon. Sides: Vertices: G, E, and O Angles: EO G

3. Classifying Triangles by Angles Acute Triangle 3 acute angles Right Triangle 1 right angle Obtuse Triangle 1 obtuse angle Equiangular Triangle 3 congruent acute angles

4. The Right Triangle E O G Hypotenuse Leg Hypotenuse – the side opposite the right angle Legs – the sides opposite the acute angles

5. Classifying Triangles by Sides ScaleneTriangle No congruent sides Isosceles Triangle At least two congruent sides Equilateral Triangle Three congruent sides

6. The IsoscelesTriangle Legs – the two congruent sides Base – the non-congruent side Vertex Angle – the angle opposite the base Base angles – the angles opposite the legs (they are congruent) E O G Leg Base