What is Radius?

• The radius is the distance from the exact center of a circle to any point on its edge (called the circumference).

• Every point on the edge is the same distance from the center, and that distance is the radius.

Important Points About Radius:

• Symbol: It is usually written as r.

• Same all around: No matter where you measure from the center to the edge, the radius will always be equal.

• It’s half of the diameter:

   r = d ÷ 2

What is Diameter?

• The diameter is a straight line that goes all the way across the circle, passing through the center.

• It connects one point on the edge (circumference) to the opposite point, cutting the circle in half.

Important Facts About Diameter:

• Symbol: Usually written as d.

• Longest line you can draw across a circle.

• The diameter is made up of two radius:

• d = 2 × r

• It’s twice as long as the radius.

What is Circumference?

• The circumference is the distance all the way around a circle.

• It’s like the perimeter of a circle — the total length of the curved edge.

Important Facts About Circumference:

• Symbol: Usually written as C.

• It’s the outer boundary or edge length of a circle.

• It’s not a straight line, but the full curve around.

favourite part/ note/ summary— Radius is the exact distance from the centre of the circle to any point of the circles edge. Radius into Radius is a Diameter and Diameter by 2 is a radius. Diameter is any straight line passing through the circle by touching the centre point. Circumference is the perimeter of the circle but instead of perimeter we call it circumference.