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. 


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