Classifying Triangles Geometry

First we will learn to classify by the ANGLES

Right triangles have ONE right angle

Acute Triangles have three acute angles Acute Angle Smaller than 90o

Obtuse Triangles have ONE obtuse angle Obtuse Angle

We will now learn to classify triangles by their sides.

Equilateral Triangles have 3 equal sides

Isosceles Triangles have 2 equal sides.

Scalene Triangles have NO equal sides.

Let’s Review: Classifying Triangles by Their Sides EQUILATERAL – 3 congruent sides ISOSCELES – at least two sides congruent SCALENE – no sides congruent EQUILATERAL ISOSCELES SCALENE

Let’s Review: Classifying Triangles by Their Angles EQUIANGULAR – all angles are congruent ACUTE – all angles are acute RIGHT – one right angle OBTUSE – one obtuse angle EQUIANGULAR ACUTE RIGHT OBTUSE

A Challenge: Classify the Triangles! ∆ABE ∆BFC ∆FCE ∆CDE ∆BCE

You have now learned that triangles can be classified by either their sides or their angles.

NOW!!! Look back at each of the types of triangles and see if you can identify a relationship between the side length and the size of its opposite angle.