Table of Contents:
Area of Circle = πr²
Diameter of Circle = 2r
Circumference of Circle = 2πr = πd
Area of Sector = πr² (θ/360) = ½ *arc * (angle in degree)
r = radius
π = 3.14
A Circle is a set of points that is formed in a closed loop, every point on which is a fixed distance from a center point. The radius of a circle is the distance from the center of a circle to any point on the circle. The distance across a circle through the center is called the diameter.
A circle is a round plane figure whose boundary or the circumference consists of points equidistant from a fixed center.
Properties of a Circle:
Center - A point inside the circle. All points on the circle are equidistant (same distance) from the center point.
Radius - The radius is the distance from the center to any point on the circle. It is half the diameter. See Radius of a circle. Diameter - The distance across the circle. The length of any chord passing through the center. It is twice the radius. See Diameter of a circle.
Circumference - The circumference is the distance around the circle.
Examples: Find the area, diameter and circumference of a circle with the given radius 4.
Step 1: Find the area.
Area = πr² = 3.14 * 4² = 3.14 * 16 = 50.24
Step 2: Find the diameter.
Diameter = 2r = 2 *4 = 8
Step 3: Find the circumference.
Circumference = πd = 3.14 *8 = 25.12