A circle is a closed, perfectly round curve. Every point on the curve is the same distance from one fixed point, the centre.
The centre is the single point exactly in the middle of the circle. Every point on the circle is the same distance from it.
Tap the dot that is equally distant from the circle’s edge to find the centre.
A radius is a line segment that connects the centre of a circle to any point on its circumference.
A wheel with a 10 cm diameter has a radius of 5 cm.
A diameter is a straight line segment that passes through the centre of a circle and joins two opposite points on the circle.
If the radius of a circle is 3 cm, its diameter is 6 cm.
Use the relation to switch between radius and diameter quickly.
If \(r = 3\text{ cm}\), then \(d = 6\text{ cm}\).
Fill in the blank: If \(r = 5\text{ cm}\), \(d = \_\_ \text{ cm}\).
The circumference is the total distance around a circle, like the line that marks a round running track.
If the edge of a round track is 400 m long, that 400 m is its circumference.
The fixed point from which every point on the circle is equally distant.
Line from the center to any point on the circle; all radii are equal.
Longest chord passing through the center; \( \text{Diameter} = 2 \times \text{Radius} \).
Perimeter of the circle; \( C = 2\pi r \).