Solving Circles
π
What is the circumference of a circle with a diameter of 5 inches?
15.7 inches
What is the area of a circle with a radius of 2 inches?
12.56 inches2
What is the measure of the inside of a circle called, and what equation is used to find it?
Area, πr2
You want to figure out how wide a tree is, and know that you can find its diameter if you know the circumference. You measure the circumference, and find out it is 18.84 feet. What is the diameter?
6 feet
What is the name of the line that passes through the center of a circle and has both endpoints on the perimeter of a circle?
Diameter
What is the circumference of a circle with a radius of 7 inches?
43.96 inches
What is the area of a circle with a diameter of 18 feet?
254.34 feet2
What is the measure of the outside of a circle called, and what equation do you use to find it?
Circumference, πd
An asteroid hit the earth and created a huge round crater. Scientists measured the distance around the crater as 78.5 miles. What is the diameter of the crater?
25 miles
What is the name of the line that has one endpoint in the center of a circle, and the other on the perimeter?
Radius
What is the diameter of a circle that has a circumference of 28.26 feet?
9 feet
14 feet
What is the radius of a circle whose diameter is 10 centimeters?
5 centimeters
The distance around a carousel is 21.98 yards. What is the radius?
3.5 yards
What formula do you need the diameter for?
Circumference, πd
How do you find the radius if you are given the circumference of a circle?
Divide the circumference by 3.14, then divide the answer by 2.
How do you find the diameter of a circle if you are given the area?
Divide the area by 3.14, then take the square root of the number that remains. Finally multiply the number by 2.
What is the diameter of a circle whose radius is 7 miles?
14 miles
A semi-circle shaped rug has a diameter of 4 feet. What is the area of the rug?
6.28 feet2
What measure of a circle do you find with the radius?
Area, πr2
What is the radius of a circle that has a circumference of 18.84 centimeters?
3 centimeters
What is the diameter of a circle that has an area of 200.96 centimeters2 ?
16 centimeters
What is the radius of a circle whose diameter is 27 inches?
13.5 inches
You order a pizza with a diameter of 14 inches. You eat 1/4 of the pizza, so there is 3/4 left. What is the area of the pizza that remains?
115.395 inches2