1. Splash Screen

2. Five-Minute Check (over Lesson 9–4) Main Idea and Vocabulary
Key Concept: Angles of a Quadrilateral
Example 1: Find a Missing Angle Measure
Key Concept: Classifying Quadrilaterals
Example 2: Classify Quadrilaterals
Example 3: Find a Missing Angle Measure
Lesson Menu

3. Classify quadrilaterals and find missing angle measures in quadrilaterals.
parallelogram
rhombus
trapezoid
rectangle
square
Main Idea/Vocabulary

4. KC

5. Find a Missing Angle Measure
Find the value of x in the quadrilateral shown.
Since the sum of the angle measures in a quadrilateral is 360°, x = 360.
Example 1

6. Find a Missing Angle Measure
x n50 = 360 Write the equation.
x = 360 Add 50, 130, and 50.
THINK What measure added to 230 equals 360?
= 360 You know that = 360.
Answer: So, the value of x is 130.
Example 1

7. Find the value of x in the quadrilateral shown.
B. 80
C. 90
D. 110 A B C D
Example 1

8. KC

9. Classify Quadrilaterals
RUGS Classify the quadrilateral of each rug below.
Answer: The first rug is a parallelogram. The second rug is a square.
Example 2

10. Classify the quadrilateral at the right.
A. rectangle
B. square
C. rhombus
D. trapezoid A B C D
Example 2

11. Find a Missing Angle Measure
SHORT RESPONSE What is the value of x in the quadrilateral below?
Read the Item You need to find the value of x.
Solve the Item Since the sum of the angle measures in a quadrilateral is 360°, x = 360.
Example 3

12. Find a Missing Angle Measure
x = 360 Write the equation.
x = 360 Add 90, 90, and 73.
THINK What measure added to 253 equals 360?
= 360 You know that = 360.
Answer: The value of x is 107.
Check  = 360 
Example 3

13. What is the value of x in the quadrilateral below?
C. 90
D. 95 A B C D
Example 3

14. End of the Lesson
End of the Lesson

15. Five-Minute Check (over Lesson 9–4) Image Bank Math Tools
Estimating Angles
Angles in Triangles
Resources

16. Classify the triangle as acute, right, or obtuse.
(over Lesson 9-4)
Classify the triangle as acute, right, or obtuse.
A. acute
B. right
C. obtuse A B C
Five Minute Check 1

17. Classify the triangle as acute, right, or obtuse.
(over Lesson 9-4)
Classify the triangle as acute, right, or obtuse.
A. acute
B. right
C. obtuse A B C
Five Minute Check 2

18. Find the value of x in the triangle.
(over Lesson 9-4)
Find the value of x in the triangle.
A. 25
B. 35
C. 45
D. 55 A B C D
Five Minute Check 3

19. Find the value of x in the triangle.
(over Lesson 9-4)
Find the value of x in the triangle.
A. 70
B. 75
C. 80
D. 95 A B C D
Five Minute Check 4

20. (over Lesson 9-4)
A triangle has sides measuring 6 centimeters, 6 centimeters, and 9 centimeters. Classify the triangle by its sides.
A. scalene
B. isosceles
C. equilateral A B C
Five Minute Check 5

21. (over Lesson 9-4)
A triangle has angles measuring 38° and 70°. What is the measure of the triangle’s third angle?
A. 12°
B. 52°
C. 72°
D. 92° A B C D
Five Minute Check 6

22. End of Custom Shows