Circles · Year 11
In Year 11 you learn: circle theorems.
A circle is all the points the same distance (the radius) from its centre. The distance round it, the circumference, and the space inside, the area, both depend on the radius and on the special number π ≈ 3.14159.
Key facts
- Diameter = 2 × radius.
- A chord joins two points on the circle; a tangent touches it at one point; an arc is part of the circumference.
- Leave answers “in terms of π” (like 25π) when asked for an exact answer.