Area And Circumference Worksheet Answers Amazing Mathematics

FINDING THE AREA AND CIRCUMFERENCE OF A CIRCLE WORKSHEET

Problem 1 :

An irrigation sprinkler waters a circular region with a radius of 14 feet. Find the circumference of the region watered by the sprinkler. Use 22/7 for π.

Problem 2 :

The diameter of a car wheel is 21 inches. Find the circumference of the wheel.

Problem 3 :

Find the diameter, radius, circumference and area of the circle shown below. use 3.14 as an approximation forπ .

Problem 4 :

A biscuit recipe calls for the dough to be rolled out and circles to be cut from the dough. The biscuit cutter has a radius of 4 cm. Find the area of the top of the biscuit once it is cut. Use 3.14 for π.

Detailed Answer Key

Problem 1 :

An irrigation sprinkler waters a circular region with a radius of 14 feet. Find the circumference of the region watered by the sprinkler. Use 22/7 for π.

Solution :

Use the formula.

C = 2πr

Substitute 14 for r.

C = 2π(14)

Substitute 22/7 for π.

C ≈ 2 x (22/7) x 14

Simplify

C ≈ 2 x (22/1) x 2

C ≈ 88

So, the circumference of the region watered by the sprinkler is about 88 feet.

Problem 2 :

The diameter of a car wheel is 21 inches. Find the circumference of the wheel.

Solution :

Radius = Diameter / 2

Radius = 21/2 inches

Use the formula.

C = 2πr

Substitute 21/2 for r.

C = 2π(21/2)

Substitute 22/7 for π.

C ≈ 2 x (22/7) x (21/2)

Simplify

C ≈ 2 x (11/1) x (3/1)

C ≈ 66

So, the circumference of the wheel is 66 inches.

Problem 3 :

Find the diameter, radius, circumference and area of the circle shown below. use 3.14 as an approximation forπ .

Solution :

From the diagram shown above, we can see that the diameter of the circle is

d = 13 - 5 = 8 cm

The radius is one half the diameter. So, the radius is

r = d/2 = 8/2 = 4 cm

Using the formula for circumference, we have

C = 2πr≈ 2(3.14)4

C≈25.1 cm

Using the formulas for area, we have

A = πr²≈ (3.14)(4)²

A≈ 50.24 square cm.

Problem 4 :

Solution :

Since the top of the biscuit is in the shape of a circle, we can use area of circle formula to find area of the top of the biscuit.

Step 1 :

Area of a circle = πr²

Radius is given in the question. That is 4 cm.

Substitute 4 for r in the above formula.

Area of the circle = π(4)²

Step 3 :

Since radius is not a multiple of 7, we can use π ≈ 3.14.

Area of the circle≈ (3.14) x (4)²

Area of the circle≈ 3.14 x 16

Area of the circle≈ 50.24 square cm.

The area of the biscuit is about 50.24 square cm.

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