1. 7.7.3 Triangles

2. Classifying Triangles
Two ways:
By the angle size
By the side length
In describing a triangle, talk about it’s angles first, then the lengths of its sides
NOTE: When no measurement is given, you have to look at the symbols. If no symbols are given, the measurement is not equal. Do not assume measurements are equal simply because they look equal.

3. Naming Triangles by Their Angles

4. Triangle Names – By Angle
Acute Triangle – All acute angles
Obtuse Triangle – One obtuse angle
Right Triangle – One right angle
Equiangular Triangle – Three congruent angles

5. Naming Triangles By Their Sides
Congruent Sides - Sides are the same length

6. Triangle Names – By Sides
Scalene Triangle – No congruent sides
Isosceles Triangle – Two congruent sides
Equilateral Triangle – Three congruent sides

7. Naming Examples

8. Your Turn! Acute Triangle – All acute angles
Obtuse Triangle – One obtuse angle
Right Triangle – One right angle
Equiangular Triangle – Three congruent angles
Scalene Triangle – No congruent sides
Isosceles Triangle – Two congruent sides
Equilateral Triangle – Three congruent sides

9. Drawing a Triangle Using Angles

10. Drawing a Triangle Using Sides

11. Your Turn!
Draw a triangle with angle measures of 45, 45, and 90. Then classify the triangle
Draw a triangle with a 1-inch side and a 2- inch side that meet at a 60 angle. Then classify the triangle
HINT: Just like when you name a triangle, start with the angle before you deal with the sides…

12. Homework
Page 286 (#4, 5, 7, 8, 9, 11, 12, 13, 15, 18, 19)