Geometry Unit 9: Circles
Name: ____________________________________________________________ Date: _________________
Directions:
You are going to be in groups of
1. Complete the table below, then answer the questions on the back.
Cookie #- Whoever made the cookie
Diameter- Measure the diameter of the cookie
Radius- Measure the radius of the cookie
Measured area- Use graph paper to trace the cookie, then count the number of squares the cookie
covered.
Measured circumference- Use the outline of the cookie to estimate the circumference.
Calculate the area and circumference of ½ and ¼ of the cookie from the measured values.
Cookie #
Diameter
Radius
Measured
Area
Measured
Circumference
Cut into ½
Cut into ¼
Geometry Unit 9: Circles
Name: ____________________________________________________________ Date: _________________
Directions:
You are going to be in groups of
1. Complete the table below, then answer the questions on the back.
Cookie #- Whoever made the cookie
Diameter- Measure the diameter of the cookie
Radius- Measure the radius of the cookie
Measured area- Use graph paper to trace the cookie, then count the number of squares the cookie
covered.
Measured circumference- Use the outline of the cookie to estimate the circumference.
Calculate the area and circumference of ½ and ¼ of the cookie from the measured values.
Cookie #
Diameter
Radius
Measured
Area
Measured
Circumference
Cut into ½
Cut into ¼
Cookie #
Diameter
Radius
Calculated
Area
Calculated
Circumference
Cut into ½
Cut into ¼
Use your measurements in the first part to determine the actual area and circumference of the whole
circle: Find the area of the whole circle (A= πr2). Find the circumference of the whole circle (C= 2πr or
C= πd).
Determine the arc length of the sector using the formula L= Өr and then the area of one sector using the
formula A = .5Өr2. Note: Ө is the angle measure of from the center of the circle.
Hypothetically what should be the circumference be of one sector? What about the area of one of the
sectors? How do each of these areas compare to the area you calculated?
Cookie #
Diameter
Radius
Calculated
Area
Calculated
Circumference
Cut into ½
Cut into ¼
Use your measurements in the first part to determine the actual area and circumference of the whole
circle: Find the area of the whole circle (A= πr2). Find the circumference of the whole circle (C= 2πr or
C= πd).
Determine the arc length of the sector using the formula L= Өr and then the area of one sector using the
formula A = .5Өr2. Note: Ө is the angle measure of from the center of the circle.
Hypothetically what should be the circumference be of one sector? What about the area of one of the
sectors? How do each of these areas compare to the area you calculated?