1. Prime Time
Circle the seven prime numbers that, when added together, equal 75.
3, 11, 14, 13, 5, 17, 12, 6, 19, 23, 7, 9
Remember a prime number is a number that has only two factors, 1 and itself.
2 is prime : 1x2

2. Prime Time Solution
= 75

3. Area of Circles
Lesson 11-6

4. Review of Circles r d
The radius of a circle is half of the diameter. Divide the diameter by 2 to get the radius.

5. Area of a Circle Area = r²
The area of a circle equals the product of pi () and the square of its radius. r
Area = r²

6. Find the Area of the Circle Round the answer to the nearest tenth.
Area = r²
A = (4²)
A = (16)
A = 50.3 cm²
4 cm

7. Find the Area of the Circle Round the answer to the nearest tenth.
Area = r²
A = (8²)
A = (64)
A = in²
8 in

8. Find the Area of the Circle Round the answer to the nearest tenth.
Area = r²
A = (5.5²)
A = (30.25)
A = 95.0 ft²
11 ft
Use the diameter to find the radius.
11 ÷ 2 = 5.5
Radius = 5.5 ft

9. Find the Area of the Circle Round the answer to the nearest tenth.
Area = r²
A = (3.25²)
A = ( )
A = 33.2 m²
6.5 m
Use the diameter to find the radius.
6.5 ÷ 2 = 3.25
Radius = 3.25 m

10. Find the area to the nearest tenth.
25.6 m
9.8 in
Area = r²
A = (12.8²)
A = (163.84)
A = m²
Area = r²
A = (9.8²)
A = (96.04)
A = in²

11. Area of a Semi-Circle Area = r² A = (13²) A = (169) A = 530.9 ft²
530.9 ft² is the area of the whole circle. How can you find the area of half the circle.
Divide the area by 2. A semi- circle is half of a circle.
Answer: ft²

12. Homework Lesson 11-6 # 2-16 even
TEST: On Friday, lesson 11-5 (area of triangles and trapezoids), lesson 11-6 (area of circles), and lesson 11-7 (we will complete this tomorrow)