Maths Question

Question

Using the calculator, find the area of a circle whose circumference is 3.14 meters

Answer 1

the underlying formula that you want to use here is

C = 2*pi*r , meaning that

r = C / 2pi

for this scenario that means that

r = 3.14 / 2pi = 0.5 meters

the question then is wanting you to use that information in order to find the Area

A = pi * r^2

A = pi * (0.5)^2

A = 0.785 square meters

Answer 2

The circumference of a circle is 2* π * r

 

The area of a circle is π * r².

 

so we know the circumference  = 3.14 meters = 2* π * r  [ Equation A]

 

pi or π we know can be found on a calculator to be 3.141592654

 

We solve the Equation A for r:

 

r = 3.14 / (2* π)

  = 3.14 / (2 *3.14) [the 3.14 cancels out]

  =  1 / 2

 

so we have all the variables for the area of a circle :  Equation B = π * r².

                                                                                             = 3.14 * ( 1/2)²

                                                                                             = 3.14 * (1/4)

                                                                                             = 3.14 * 0.25

                                                                                             = 0.785 meters

 

Area of a circle whose circumference is 3.14 meters= 0.785 meters     or  0.25 π