440 likes | 1.2k Views
Finding Circumference for 4 th and 5 th Grade. By Andrea Klee. What Is Circumference. Circumference is the distance all the way around a circle. The equation to find circumference is 2 r or multiplied by the diameter of the circle. Some Terms Defined.
E N D
Finding Circumferencefor 4th and 5th Grade By Andrea Klee
What Is Circumference • Circumference is the distance all the way around a circle. • The equation to find circumference is 2r or multiplied by the diameter of the circle.
Some Terms Defined • is said as pie, like the kind you eat • about 3.14 • r is the radius of a circle • or half the distance across a circle • d is the diameter of a circle • or the distance all the way across a circle • or two radii added together
How To Find Circumference • If you have the radius: • Multiply the radius by 2 to get the diameter. • Multiply this answer by 3.14 ( ). • If you have the diameter: • Multiply the diameter by 3.14 ().
Let’s Try A Problem Find the diameter or the radius. We are going to find the radius. What is the radius of this circle?
Problem Continued • The radius is 5. • Next, multiply the radius by 2 to get the diameter. • Last, multiply the diameter by or 3.14.
Problem Solved • The circumference of the circle is 31.4.
Here’s Another Problem • Find the circumference of this circle.
Solution • The diameter is 6. • Multiply the diameter by (3.14). • The Circumference is 18.84.
Links • Math.com has everything you might want to know about the parts of circles. • This site defines circle, pie, circumference, diameter, and radius. • http://www.math.com/tables/geometry/circles.htm
Links • Prime Mathematics Enrichment is a magazine that has fun projects to do involving circles. • http://www.nrich.maths.org.uk/prime/feb01/magazine.html
Links • Math Forum’s Ask Dr. Math • This page is a letter sent to Dr. Math asking how the circumference of the Earth was first measured. This offers a little history about circumference. • http://mathforum.org/library/drmath/view/58988.html