1. Classifying Triangles

2. Classifying Triangles By Their Angles Acute Right Obtuse

3. Acute Triangles Acute triangles have three acute angles

4. Right Triangles Right triangles have one right angle

5. Obtuse Triangles Obtuse triangles have one obtuse angle

6. The Sum of Angles in a Triangle The sum of the measures of any triangle is 180°. To find a missing angle in a triangle: 1.Add the two given angles together. 2.Subtract the sum of the two angles from 180 o (since the total of all three angles must equal 180 o ). 55 o 45 o x 55 + 45 100 180 - 100 80 x= 80 o Check your work by adding the 3 angles together. 55 45 + 80 180

7. Triangle Degrees The sum of the measures of any triangle is 180°. 70° x What is the measure of x? x= 20 o

8. Triangle Degrees The sum of the measures of any triangle is 180°. 45° x What is the measure of x? x= 45 o

9. Triangle Degrees The sum of the measures of any triangle is 180°. What is the measure of x? x 60°50° x= 70 o