Circle Diameter Concept

Diameter of a Circle

• Definition: A line that cuts a circle into two equal halves, passing through the center and ending on the opposite side.
• Property: The diameter is the longest chord of a circle.
• Infinite diameters: A circle has an infinite number of diameters, but each has the same length.

Key Features of a Circle

• Radius: A line segment starting at the center and ending at any point on the circumference. Symbol: r.
• Diameter: A line segment starting at one point on the circumference, passing through the center, and ending on the other side. Symbol: d.
• Circumference: The distance along the edge of a circle. Symbol: C.
• Area: The total space inside the circle. Symbol: A.

Radius and Diameter

• Relationship: The radius is half the length of the diameter.
• Formula: diameter = 2 × radius.

Circumference

• Definition: The length of the border of a circle.
• Formula: Circumference = π × diameter.
• Property: The circumference has a consistent ratio with the diameter.

Area of a Circle

• Definition: The 2-D space held within a circle.
• Formula: Area = π × radius².
• Property: The area has a consistent relationship with the radius and diameter.

Finding the Diameter

• From Radius: diameter = 2 × radius.
• From Circumference: diameter = Circumference ÷ π.
• From Area: diameter = √(4 × Area ÷ π).

Practice Questions

• Examples and exercises to find the diameter using radius, circumference, and area.