Measurements
Formulas and Symbols
Area
Circles
Problem Solving
100
What is this?
Diameter
100
What is π rounded to 2 decimals?
3.14
100
Find the area:
r = 5 cm
78.5 cm2
100
The diameter of this circle is 14 cm. What is the radius?
The radius is 7 cm.
100
The diameter of the basketball is 15 cm. The diameter of the hoop is 17 cm. How much bigger is the hoop's circumference than the basketball?
Ball: C = 47.1 cm2
Hoop: C = 53.38 cm2
Difference = 6.28 cm2
200
What is the perimeter of a circle called?
Circumference?
200
True or False: π is the same for every circle
True
Pi is the relationship between diameter and circumference.
200
True of False:
A = π x r x 2
False
A = π r2
200
The circumference of this circle is 18.84 cm. What is the diameter?
The diameter is 6 cm.
200
The radius of this pizza is 10 cm. What is the area?
A = 314 cm2
300
Which circle measurement is half of another?
Radius - it is half of the diameter
300
What is the formula for circumference?
C = π d
C = 2π r
300
Find the area:
d = 6cm
28.26 cm2
300
The radius of the circle is 2 cm. What is the area?
A = 12.56 cm2
300
The diameter of a circular park is 98 m. Find the cost of fencing it at $4 per meter.
C = 307.72
Cost = $1.230.88
400
Which circle measurement is in the formula for area of a circle?
radius
400
Why are there two formulas to find circumference?
You can use diameter or radius.
400
Find the area:
C = 10 cm
about 7.94 cm2
400
The diameter of this circle is 16 cm. What is the area?
A = 200.96 cm2
400
The diameter of a cart wheel is 2.1 m. Find the distance traveled when it completes 100 revolutions.
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C = 6.594 m
Distance = 659.4 m
500
Which circle measurement is about 3 times as big as the diameter?
Circumference
500
What is the formula for finding the area of a circle?
A = π r2
500
Find the area:
C = 12
about 11.34 cm2
500
The radius of a circle is 21 cm. What is the circumference?
C = 65.94 cm2
500
A goat is tethered by a rope 3.5 m long. Find the maximum area that the goat can graze.
A = 38.465 m2