1. Triangles
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2. Warm Up
Tell if each figure is a polygon. If it is not a polygon, explain why. If it is a polygon, name it and tell if it is regular.
1).
2).
3).

3. Warm Up
Tell if each figure is a polygon. If it is not a polygon, explain why. If it is a polygon, name it and tell if it is regular.
1).
2).
3).
4).
Nonagon,
Not regular
Quadrilateral, regular
Pentagon, regular
Not a polygon, not made of line segments.

4. Triangle Flippable Right Acute Obtuse Classifying Triangles by Angles
Classifying Triangles by Sides
Equilateral
Isosceles
Scalene

5. Classification of Triangles by Angles
Acute Triangle
Right Triangle
Obtuse Triangle
Exactly one interior angle measures 90°.
Exactly one interior angle is obtuse.
All three interior angles are acute.

6. Classification of Triangles by Sides
Equilateral Triangle
Scalene
Triangle
Isosceles
Triangle
All sides have different lengths.
Two sides are the same length.
All three sides are the same length.

7. Practice
Classify each triangle by its angles and its sides.
Obtuse and scalene
1).
Acute and equilateral
2).
Right and scalene
3).
4).
Acute and isosceles

8. Interior Angles of a Triangle
The sum of the measures of the interior angles of a triangle is 180°.

9. Find the missing angle for each triangle.
Practice
Find the missing angle for each triangle.
119 degrees
80 degrees
1).
2). x x
32 degrees
3). x

10. How are triangles classified?
Closure
How are triangles classified?