Circumference
Area
Formulas & Ratios
Area of the Shaded Region
Composite Figures
100
Define circumference
The distance around the circle
100
What is the formula for the area of a circle?
A=πr²
100
What is the value of π?
3.14159265359 or 3.14 or 22/7
100
What are concentric circles?
Two circles with the same center
100
What is a semicircle
Half of a circle
200
What is the formula for circumference
C=2πr or C=πd
200
Abdiel is selling pizza at school. The pizzas are 10 inches in diameter. Calculate the area of one pizza.
A=π10²
A=100π or 314 inches²
200
What is the ratio for π?
C/d
200
What is the annulus?
The distance between concentric circles
200
Write the formula to find the area of a composite figure consisting of a trapezoid and a semicircle.
A=.5(b1+b2)*h + .5(πr²)
300
Calculate the circumference of a circle with a radius of 12 inches. Use 3.14 for π and round to the nearest hundredth if necessary.
75.36 inches
300
Calculate the area of a circle with a radius of 3 feet. Use 3.14 for π.
28.26 ft²
300
What formula can you use to find the radius from the diameter?
r=2d
300
Find the area of the shaded region of the rectangle in square inches.
A=lw-πr²
A=(50*20)-π8²
A=1000-200.96
A=799.04 in²
300
Find the area of the composite shape below.
A=4*3 + (9-4)*6
A=12 + 30
A=42cm²
400
Calculate the diameter of a circle with a circumference of 628 cm. Use 3.14 for π.
200 cm
400
A circular marble tabletop has a diameter of 30 inches. What is the approximate area of the circular marble tabletop in square inches?
A = π*15²
A=225π
A=706.5 in²
400
Write an expression that is equivalent to π when you know that the circumference of a circle is 100 cm.
π=100/d
400
Aaron plants flowers in a circular bed, represented by the unshaded circle in the diagram. He builds a circular patio around the flowers, represented by the shaded portion of the diagram. Both circles share the same center. What is the area of the patio? Use 3.14 for π.
A=π7² - π3²
A=49π - 9π
A=40π
A=125.6 cm²
400
Find the area of the composite figure below:
196.48m²
500
Approximately how much fencing is needed to enclose a circular pond with a diameter of 20 feet?
62.8 feet
500
Jeremy and Dilan would like enclose a circular portion of the playground as an enclosure for them and their friends to play in. Determine the area of the enclosure if they had 62.8π feet of fencing. Leave your answer in terms of π.
62.8π=2πr
r=31.4 ft.
A=π*31.4²
A=985.96 ft²
500
If a 10 inch pizza costs $10.00, what is the cost of pizza per square inch?
$.13 per square inch of pizza
500
Two small circles are drawn that touch each other, and both circles touch the large circle. What is the area of the shaded region in cm².
A=13²π - 9²π - 4²π
A=169π - 81π - 16π
A=42π
A=21.98 cm²
500
Mr. Lee is building a miniature basketball court for his desk. The key of the court is constructed using a rectangle and a semicircle. If the length of the rectangle is 15 in. and the diameter of the semicircle is 10 in., what is the area of the key that will take up Mr. Lee's desk?
A=lw+.5(πr²)
A=(15)(10)+.5(π5²)
A=150+.5(π25)
A=150+39.25
A=189.25 in²