Question

Area of a Circle

Instruction Active

Finding Area from Circumference

The circumference of a circular pond in the park is 120 meters. Find the area

The formula for circumference is C = id

What is the value of the diameter rounded to the nearest whole number?

What is the value of the radius rounded to the nearest whole number?

The formula for area is = r2

What is the approximate area of the circular pond rounded to the nearest whole number?

m

Answer 1

i) Diameter = 38 meters

ii) Radius = 19 meters

iii) Area = 361 m²

Explanation:

i) According to the formula given in the question, the formula for the circumference, C = πD

C = 120 meters

Diameter, D = 120/π

D = 38 meters

ii) The value of the radius

Radius, r = (Diameter, D)/2

r = 38/2

r = 19 meters

iii) What is the approximate area

From the question, the expression for the area is A = r²

Area, A = 19²

A = 361 meters

Answer 2

The diameter of the pond is 38 m.

The radius of the pond is 19 m.

The area of the pond is 361 m^2.

Explanation:

We know that the circumference C of a circle is equal to

`C=\pi D`

In this case, C is equal to 120 m.

The diameter is then:

`D=C/\pi=120/3.14=38.21\approx 38`

Rounded to the nearest whole number, the diameter is D=38 metres.

The radius is equal to half the diameter, so the radius of this pond is R=19 metres.

`R=D/2=38/2=19`

The area can be calculated from the radius as:

`A=r^2=19^2=361`

The area is 361 m^2