The area and circumference of a circle

​After studying this topic, students are able to:

​• Know the definition of a circle and the names of its part

• Know and use formulae for the circumference and area of circle

Terms:​

​circle: a closed shape formed by tracing a point that moves in a plane such that its distance from a given point (center) is constant.

radius: a line segment from the center to the circumference of a circle or sphere.

​chord: a line segment whose endpoints both lie on a circular arc. diameter is the longest chord in a circle

​diameter: any line segment that passes through the center of the circle and whose endpoints lie on the circle

​tangent: a line which touches the circle at only one point

​secant: a line that intersects a circle at two distinct points

Circumference: the distance around the outside of the circle. It is like the perimeter of other shapes like squares.