HOW MANY SIDES ARE THERE, AND WHAT IS THEIR ANGLE?

There are two ways to classify triangles: By their sides By their angles

Classifying Triangles by their sides There are three types: Scalene Isosceles Equilateral

1. SCALENE No congruent sides (No sides are equal ) 12in.

2. ISOSCELES Two of the sides are congruent, (equal) 5 in. 10 in.

3. EQUILATERAL SIDES Three congruent sides, (all the sides are equal) 9 in. 9 in. 9 in.

Classifying Triangles by their Angles There are three more types: Acute Obtuse Right

1. Acute Triangles Acute Triangles have 3 acute angles 60° 60° 60° 60° 60° 60° 60°

2. OBTUSE TRIANGLES Obtuse triangles have one obtuse (greater that 90 °) angle 110° 30° 40°

3. RIGHT TRIANGLES Right Triangles have one right angle (90°) 45° 90° 45°

Now…let’s practice what we have learned…. What type of triangle has three congruent sides? A. Isosceles Triangle B. Equilateral Triangle C. Scalene Triangle What type of triangle has one 90° angle and two acute angles? A. Acute triangle B. Obtuse triangle C. Right Triangle

Classify the following according to sides and angles: and then check your work with the ruler and protractor Scalene, right triangle

Classification #2 Check your answer with the ruler and protractor. Equilateral, acute triangle

Classify the following and check with a ruler and protractor. Isosceles, right triangle

Classify the following by both sides and angles: Equilateral, acute triangle