Triangles

1
Triangles

• Lesson 10-4

2
Triangle

• A triangle is a figure that has 3 sides and 3
  angles. The sum of the measure of the angles is
  180
• mlt1 mlt2 mlt3 180

1
2
3
3
Find the missing angle measure

• lt1 50 lt2 75 lt3 ?

4
Find the missing angle measure

• lt1 50 lt2 75 lt3 ?
• 50 75 125
• 180 125 55

5
Classify Triangles Using Angles

• Acute Triangle
• Properties All acute angles.

6
Classify Triangles Using Angles

• Right Triangle
• Properties 1 right angle.

7
Classify Triangles Using Angles

• Obtuse Triangle
• Properties 1 obtuse angle.

8
Classify Triangles Using Sides

• Scalene Triangle
• Properties No congruent sides.

9
Classify Triangles Using Sides

• Isosceles Triangle
• Properties At least 2 congruent sides.

This symbol represents that the sides are
congruent.
10
Classify Triangles Using Sides

• Equilateral Triangle
• Properties 3 congruent sides.

11
Naming Triangles

• Triangles have a 2 part name.
• The first part of the name, names the angles
  (acute, obtuse, or right)
• The second part of the name, names the sides
  (scalene, isosceles, or equilateral)
• Example Obtuse Scalene

12
Name the Triangle

• Acute Scalene

13
Name the Triangle

• Right Scalene

14
Name the Triangle

• Acute Equilateral

15
Find the missing angle. Then classify the
triangle as acute, right, or obtuse.

• 50 , right

x
40
16
Find the missing angle. Then classify the
triangle as acute, right, or obtuse.

• 135 , obtuse

20
25
x
17
Find the missing angle. Then classify the
triangle as acute, right, or obtuse.

• 20 , obtuse

30
x
130
18
Dont Forget

• Class Assignment
• Old Blue - read p. 428-429 complete p. 430-431
  (1-28)
• IXL Lesson P7 (minimum 80)
• Homework Old Blue p. 588 - Lesson 10-4