A circle is a set of points in a plane that are a fixed distance from the center.
A radius is a line segment with one endpoint at the center of the circle and the other endpoint on the circle. The length of a radius is called the radius of the circle.
A diameter of a circle is a line segment that passes through the center of the circle and whose endpoints lie on the circle. The length of the diameter is twice the length of the radius. The length of a diameter is called the diameter of the circle.
The circumference of a circle is the distance around the circle.
The above explained points have been illustrated in the diagram given below.
The ratio of the circumference to the diameter is the same for all circles.
This ratio is called π or pi, and you can approximate it as 3.14 or as . You can use π to find a formula for circumference.
For any circle, C/d = π. Solve the equation for C to give an equation for the circumference of a circle in terms of the diameter.
The ratio of the circumference to the diameter is π.
C/d = π
Multiply both sides by d.
(C/d) x d = π x d
C = πd
The diameter of a circle is twice the radius. You can use the equation C = πd to find a formula for the circumference C in terms of the radius r.
C = π(2r) = 2πr
The two equivalent formulas for circumference are C = πd and C = 2πr.
An irrigation sprinkler waters a circular region with a radius of 14 feet. Find the circumference of the region watered by the sprinkler. Use 22/7 for π.
Use the formula.
C = 2πr
Plug 14 for r
C = 2π(14)
Plug 22/7 for π
C ≈ 2 x (22/7) x 14
C ≈ 2 x (22/1) x 2
C ≈ 88
So, the circumference of the region watered by the sprinkler is about 88 feet.
Apart from the stuff given above, if you need any other stuff in math, please use our google custom search here.
You can also visit the following web pages on different stuff in math.
APTITUDE TESTS ONLINE
ACT MATH ONLINE TEST
TRANSFORMATIONS OF FUNCTIONS
ORDER OF OPERATIONS
Analytical geometry calculators
MATH FOR KIDS
Word problems on linear equations
Trigonometry word problems
Word problems on mixed fractrions
Ratio and proportion shortcuts
Converting repeating decimals in to fractions