GCSE Circle


A circle is a locus of all points which are at the same distance from the fixed point. This distance from the center to each point is called the radius.

Different parts of a circle:


Centre: Centre of a circle is the point that is equidistant from all points of the circle.

Radius: A line from the center of a circle to the circumference of a circle.

Diameter: Diameter is a line that passes through the center of the circle and whose endpoints lie on the circle.

Diameter (d) = 2 x radius

Chord: A Chord is a line segment that connects two points present on the circumference of the circle. If the chord passes through the center of the circle, then it is called the diameter.

Tangent: A line that touches the circumference of a circle at any one point is called Tangent.

Arc (Major and Minor): A small part of the circumference of a circle.

Sector (Major and Minor): A part of the circle enclosed by two radii (r1 and r2) of the circle. A sector means a portion of the circle. The arc is just part of the circumference, but the sector is part of the area.

Area of a Circle:

The amount of space occupied by the circle is defined as the area of a circle.

Area = r2 =  (square units)

Where r= radius


Circumference of the Circle:

Distance around the circle is defined as circumference of a circle.

Circumference of a circle, C=2r= d (units)

Where r= radius




A semi-circle is formed when the circle is divided into two parts.

Area of Semicircle:

The area of a semicircle is equal to half of the area of the circle.

Area of semicircle, A = πr2/2 square units

Circumference of Semicircle:

Circumference or perimeter of a semicircle is equal to the half of the circumference of the circle.

Circumference of the semicircle, C = 2πr/2 = π x r units






GCSE Maths complete online solution: https://gcsemaths4fun.co.uk/blog/2020/02/01/benefits-of-gcsemaths4fun-co-uk-in-gcse-preparation/

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