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Maths

Circles - Higher

If you have worked through Circles, you already know how to find the area and circumference of a circle. Now we are going to explain how to calculate the length of an arc and the area of a sector of a circle.

Words associated with circles

You should already know the meanings of the words radius, diameter, circumference, tangent, arc, chord, sector and segment. If you are not sure about any of them, have a look at the Revision Bite on Circles.

Segments and arcs

When a chord divides a circle into segments, it produces a minor segment and major segment. It also divides the circumference into a minor arc and major arc.

image: circle: divided by a line near the top half, smaller half: minor segment, larger half: major segment, arrows shows out-side edge of major segment: major arcm, out-side edge of minor segment: minor arc.

Sectors

In a similar way, two radiuses (or radii) divide the circle into a minor sector and major sector.

image: circle, triangular segment: minor sector, rest of circle: major sector.

Back to Shape, space and measures index

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