Circumference and Area of a Circle

If you would like a little refreshment about the circumference and area of a circle than this website will help you.

Circumference

Circumference is the distance around a circle (well at least in this case).

The formula for circumference is 2Pi(r) OR Pi(d).


Example of Circumference

  • Lets say you have a can of fruit and you want to find the circumference of it, so you find the measurements which are 3 inches in diameter and 5 inches in height.
  • If we have to multiply the diameter by Pi and Pi is 3.14
  • Then, we should get 9.42 inches
  • Next, if you want to do 2Pi(r) then you have to divide the diameter by 2 to get the radius.
  • The radius is always half of the diameter
  • So, if you find radius then it should be 1.5
  • The formula is 2Pi(r)
  • So, if you already know 1.5 x 1.5 is 3 than you just multiply that by 3.14
  • And you get 9.42 inches.

May help a little more.

Area

The area of a circle has multiple steps to it.The formula for area of a circle is A=Pi(r) OR A=Pi * r * r.

Example of Area of a Circle

Saras pizza place makes pizzas that have a diameter of 8 inches and she wants to figure out how much space she needs on her counter.We need to figure out what the area is of the pizza.The formula for area is A=Pi*r*r So, what we have to do first is find the radius We have to divide 8 by 2 and you should get 4.Then, you have to multiply 4x4=16 because 4 to the second power equals 16You take 16 and multiply that by Pi=(3.14)You should get 50.24 inches.

This might explain a little better

STAAR Question Circumference

Rose has to measure things around her house for a project for school. She measures one of her moms cars tires. It has a diameter of 16 inches. You are only aloud to use the formula C=2Pi(r). Use 3.14 for Pi. She has to find the circumference of her household items. Figure out the circumference.

Solution and Answer to STAAR Question Circumference

Circumference= 16/2=8      8*8=64    64*3.14=200.96