There are 7 types of triangles classified by their sides and angles: equilateral triangles have 3 congruent sides; isosceles triangles have 2 congruent sides; scalene triangles have no congruent sides; equiangular triangles have 3 congruent angles; acute triangles have 3 acute angles; obtuse triangles have 1 obtuse angle; and right triangles have 1 right angle. The lesson teaches how to classify triangles based on these properties of their sides and angles.

1. Lesson 5.1
Classifying
Triangles
Today, you will learn to…
* classify triangles by their sides and
angles
* find measures in triangles

2. A
B
C
∆ ABC

3. Equilateral Triangle
3 congruent sides

4. Isosceles Triangle
2 congruent sides

5. Scalene Triangle
no congruent sides

6. Equiangular Triangle
3 congruent angles

7. Acute Triangle
3 acute angles
60°
70°
50°

8. Obtuse Triangle
1 obtuse angle
95°
25°60°

9. Right Triangle
1 right angle
60°
30°

10. We classify triangles by their
sides and angles.
SIDES ANGLES
Equilateral
Isosceles
Scalene
Equiangular
Acute
Obtuse
Right