1. Unit 4B Measure Figures
Lesson 2
Area of Circles

3. Lesson 2: Area of Circles
Objective: Swbat find the area of a circle.
Do Now: Find the radius or diameter.
Diameter = 6 cm
Radius = 11 ft
Find the circumference of each circle.
5 cm
13 in

4. Lesson 2: Area of Circles
Definition Semicircle is half of a circle.

5. Lesson 2: Area of Circles
Activity: How to find the Area of a Circle? Identify the radius of the circle. Identify the diameter of the circle. Find the circumference of the circle. Use the Area of a Rectangle to find the Area of a Circle 1. Arrange the sectors of the circle to make a rectangle. 2. How do you find the Area of Rectangle? 3. Measure the base and height 4.. Find the Area of the Rectangle

6. Lesson 2: Area of Circles
Use the Area of a Rectangle to find the Area of a Circle 1. Arrange the sectors of the circle to make a rectangle. 2. How do you find the Area of Rectangle? 3. Measure the base and height 4.. Find the Area of the Rectangle

7. Lesson 2: Area of Circles
Area of a Circle Area of the Rectangle A = bh Base of Rectangle A = (1 ∙ C ) r Height of Rectangle 2 Circumference in terms of radius A = 1∙ 2∏r ∙ r 2 Simplify A = ∏r2

8. Lesson 2: Area of Circles
The Area of a Circle equals the product of pi and the square of its radius. Area of a Circle Formula Area = Find the area of the circle: Area = π( __)2 = __π = _____ in2
3 in.

9. Lesson 2: Area of Circles
Area of a Circle Formula Area = πr2 Find the area of the circle given a diameter: Radius = ___ = 2 Area = π( __)2 = __π = _____ in2
8 in.

10. Lesson 2: Area of Circles
Try It! Area = ∏r
5 in.
14 cm

11. Lesson 2: Area of Circles
Try It! Area of a semicircle = ____ A semicircle with diameter of 6 cm.

12. Lesson 2: Area of Circles
Real-World Problem On a basketball court, there is a semicircle above the free-throw line that has a radius of 6 feet. Find the area of the semicircle.

13. Lesson 2: Area of Circles
Real-World Problem Find the area of the face of a quarter in millimeters.

14. Classwork
Guided Practice # 1-5 Independent Practice #1 – 12 Problem Solving Practice #1 -6

15. Closure
Question: How do you find the area of a circle and semicircle? Exit Ticket Homework: Practice #1 -14

16. Exit Ticket Find the area of a circle with a radius of 10 cm.
Find the area of a circle with a diameter of 8 cm.
Find the area of a semicircle with a radius of 3 cm.

17. Homework