1. MCC.4.G.1-2
All About Triangles

2. What is a triangle?
A triangle is a figure that has 3 sides and 3 angles.

3. How do we classify triangles?
We classify triangles in 2 different ways:
#1: Based on the length of the sides
#2: Based on the angles

4. Length of Sides
There are 3 different triangles based on length of sides:
-Equilateral
-Isosceles
-Scalene

5. Equilateral Triangle
An equilateral triangle has 3 sides that are the same length.

6. Isosceles Triangle
An isosceles triangle has 2 equal sides.

7. Scalene Triangle
A scalene triangle has no equal sides.

8. “My Many Triangles” Task
Cut out each triangle.
Sort these into groups according to their length of sides.
Use a ruler to accurately measure.

9. Measurement of Angles
There are 3 different types of triangles based on measurement of angles:
-Acute
-Obtuse
-Right

10. Acute Triangle
All angles are less than 90°

11. Obtuse Triangle
Has one angle greater than 90°

12. Right Triangle
Has a right angle (90°)

13. “My Many Triangles” Task
Sort these into groups according to their angles.
Use your index card to accurately measure the angles.