1. Lesson 10.1, For use with pages 521-526
Find the area of the triangle and rectangle.
1. 2.
3 ft 15 m
4 ft
15 m

2. Lesson 10.1, For use with pages 521-526
Find the area of the triangle and rectangle.
1. 2.
3 ft 15 m
4 ft
15 m
ANSWER 6 ft2
ANSWER 225 m2

3. Bell Work
Talk with your partner about the homework
that is due today.
 If it is a book assignment, please open your book
so you can look back at the question.
Discuss each of the following questions with
each problem from homework:
How did you solve the problem?
Why did you solve it that way?
What did you get for your answer?

4. Circles
10.2
How would you define a circle?
How do you know where the
center of a circle is located?

5. The distance across the center of a circle is
called the diameter. (Line segment AB below)
The distance from the center to the edge of a
circle is called the radius. (Segment CD)
TWO RADII = One Diameter
or the radius is ½ diameter A
D
D÷2=R
C g
B

6. The distance around a circle is called the
circumference.
C = π d or C = π 2 r

7. C = π d or C = π 2 r
Find the circumference: (round to nearest tenth)
r = 4 in C=π2r
C = 3.14 x 2 x 4
C= 25.1 in

8. C = π d or C = π 2 r
Find the circumference:(round to nearest tenth)
d = 7 cm C=πd
C = 3.14 x 7
C= 22.0 cm

9. Area of a circle is still the number of
SQUARE UNITS inside the closed figure.
The area formula is A = π r2
read Pi times the radius squared and it
means Pi x radius x radius

10. A = π r2
Find the area of the circle below
A = π r2
D = 10 in A = 3.14 x 52
A=78.5 in sq

11. A = π r2
Find the area of the circle below
A = π r2
r = 3 cm
A = 3.14 x 32
A= 28.3 in sq

12. GUIDED PRACTICE for Examples 1 and 2
Find the area and circumference of the circle.
Use 3.14 for л.
1. r = 7 ft
SOLUTION
A = лr 2 C = 2лr
= 3.14 (7)2 = 2x 3.14 x 7
= 153.9 ft2. = 44.0 ft

13. GUIDED PRACTICE for Examples 1 and 2
Find the area and circumference of the circle.
Use 3.14 for л.
2. d = 44 m
SOLUTION
A = лr 2 C = лd
= 3.14 (22)2 = 3.14 x 44
= 1519.8 m2. = 138.2 m

14. Homework
Page 529 #4-7
 Find both circumference and area for each
problem.
 ROUND TO THE NEAREST TENTH
 SHOW YOUR WORK!