Click the mouse button or press the
Space Bar to display the answers.
Objective
Find the areas of circles
Vocabulary
Circumference
The distance around a circle
Symbols
Pi
Approximately 3.14
You are to use the  key on the calculator
Example 1 Find Areas of Circles
Example 2 Find Area of Circles
Example 3 Use Area to Solve a Problem
Find the area of the circle to
the nearest hundredth
A =   (5 yd)2
Draw the circle and label the
radius
Write formula for area of circle
Replace r with 5 yd
1/3
Find the area of the circle to
the nearest hundredth
A =   (5 yd)2
A =   25
yd2
Answer:
A = 78.54 yd2
Follow Order of Operations
P
E
MD
AS
Must do exponents before
multiplying
Find square of 5 yd
Multiply by 
1/3
Find the area of the circle to the nearest hundredth
Answer: 50.27 cm2
1/3
Find the area of the circle to
the nearest hundredth
Draw the circle and label the
diameter
Remember: Diameter goes all
the way across the circle and
twice the radius
Write formula for area of circle
2/3
Find the area of the circle to
the nearest hundredth
A =   (5.4 in)2
Since diameter is given must divide
the diameter by 2 to find radius
10.8  2 = 5.4
Replace r with 5.4 in
2/3
Find the area of the circle to
the nearest hundredth
A =   (5.4
in)2
A =   29.18 in2
Answer:
A = 91.61 in2
Follow Order of Operations
P
E
MD
AS
Must do exponents before
multiplying
Find square of 5.4 in
Multiply by 
2/3
Find the area of the circle to the nearest hundredth
Answer: 124.69 m2
2/3
CRATERS The Chicxulub Crater in the Yucatan
Peninsula, Mexico, was caused by a crashing asteroid
or comet about 65 million years ago. If the diameter
measures 300 kilometers, what is the area covered by
the crater?
Draw the circle and label the
diameter
300 km
Remember: Diameter goes all
the way across the circle and
twice the radius
Write formula for area of circle
3/3
300 km
A =   (150 km)2
Since diameter is given must divide
the diameter by 2 to find radius
300  2 = 150
Replace r with 150 km
3/3
300 km
A =   (150 km)2
A =   22,500 km2
Follow Order of Operations
P
E
MD
AS
Must do exponents before
multiplying
Answer:
A = 70,685.83 km2
Find square of 150 km
Multiply by 
3/3
SWIMMING POOL A new children’s circular swimming
pool being built at a local recreation center has a
diameter of 24 feet. How much area does the new
pool cover?
Answer: 452.39 ft2
3/3
Assignment
Lesson 14:3
Area of Circles
4 - 16 All