Circles

A circle is every point at the same distance from one point, its centre. That distance is the radius; the diameter goes across through the centre and is two radii; the circumference is the way round. A circle's area is π × radius × radius.

Depth 1 · Foundation

You know a circle is every point at the same distance from its centre, can tell a radius from a diameter (two radii), and know the circumference is the way round.

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Depths of understanding

1
Foundation
You know a circle is every point at the same distance from its centre, can tell a radius from a diameter (two radii), and know the circumference is the way round.
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- CirclesGeometry Level 1: Shapes and Space
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Points and linesA radius and a diameter are line segments, and the centre is a point.LengthA circle's radius, diameter and circumference are lengths you can measure.
2
Deeper
You can find a circle's area as π × radius × radius, and see why: thin slices laid head to tail make almost a rectangle, one radius high and half the circumference long.
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- The Area of a CircleGeometry Level 1: Shapes and Space
Master depth 1 first
Pi (π)The area of a circle is π × radius × radius.Area, depth 3A circle's area is found by cutting it into slices and laying them out as an almost-rectangle, the way a parallelogram is cut and moved.

Your path here

What's still between you and Circles, depth 1, in the order you can learn it.

Where it fits

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Points and lines LengthMeasurement

This concept

CirclesGeometry

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Pi (π)Solid shapes

Builds onThis conceptOpens upPoints and lines LengthMeasurement CirclesGeometry Pi (π)Solid shapes