5. A circle has a centre.
The line joining any two points in a circle is the
chord.
The longest chord which passes through the
centre of the circle is diameter.
Radius is half the diameter.
6. PERIMETER OF A CIRCLE
perimeter = 2 r ; where ≈ 3.14
r = radius of the circle.
7. AREA OF A CIRCLE
Area of a circle = r² ;where r is the radius
8. ARC LENGTH
The length of an arc of a circle is that
part of the perimeter of the circle as the central
angle is 360°.
9. Arc length = x
360 ; where r is the radius
x is the central angle
2 r
10. SECTOR
It is a part of circle extending to the centre.
