1. Classify ΔRST . A. acute B. equiangular C. obtuse D. right
5-Minute Check 1

2. Find y if ΔRST is an isosceles triangle with RS  RT.
___ 12
5-Minute Check 2

3. Find x if ΔABC is an equilateral triangle.4
5-Minute Check 3

4. A. ΔABC
B. ΔACB
C. ΔADC
D. ΔCAB
5-Minute Check 4

5. Classify ΔMNO as scalene, isosceles, or equilateral if MN = 12, NO = 9, and MO = 15.
5-Minute Check 5

6. You classified triangles by their side or angle measures.
Apply the Triangle Angle-Sum Theorem.
Apply the Exterior Angle Theorem.
Then/Now

7. remote interior angles
auxiliary line
exterior angle
remote interior angles
Vocabulary

8. Concept 1

9. Use the Triangle Angle-Sum Theorem
SOFTBALL The diagram shows the path of the softball in a drill developed by four players. Find the measure of each numbered angle.
Example 1

10. Find the measure of 3. 57
Example 1

11. Concept 3

12. GARDENING Find the measure of FLW in the fenced flower garden shown.
Use the Exterior Angle Theorem
GARDENING Find the measure of FLW in the fenced flower garden shown.
Example 2

13. The piece of quilt fabric is in the shape of a right triangle
The piece of quilt fabric is in the shape of a right triangle. Find the measure of ACD. 40
Example 2

14. Concept 5

15. Find the measure of each numbered angle.
Find Angle Measures in Right Triangles
Find the measure of each numbered angle.
Example 3

16. Find m3. 85
Example 3