Regular polygons and circles

There are 118 NRICH Mathematical resources connected to Regular polygons and circles
Ford Circles
problem

Ford Circles

Age
16 to 18
Challenge level
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Can you find the link between these beautiful circle patterns and Farey Sequences?
Bicentric Quadrilaterals
problem

Bicentric Quadrilaterals

Age
14 to 16
Challenge level
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Investigate the properties of quadrilaterals which can be drawn with a circle just touching each side and another circle just touching each vertex.
Curvy areas
problem

Curvy areas

Age
14 to 16
Challenge level
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Have a go at creating these images based on circles. What do you notice about the areas of the different sections?
Partly Circles
problem

Partly Circles

Age
14 to 16
Challenge level
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What is the same and what is different about these circle questions? What connections can you make?
Efficient packing
problem

Efficient packing

Age
14 to 16
Challenge level
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How efficiently can you pack together disks?
Shaping Up
problem

Shaping Up

Age
7 to 11
Challenge level
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Are all the possible combinations of two shapes included in this set of 27 cards? How do you know?
Lighting up time
problem

Lighting up time

Age
7 to 14
Challenge level
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A very mathematical light - what can you see?
Overlapping Again
problem

Overlapping Again

Age
7 to 11
Challenge level
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What shape is the overlap when you slide one of these shapes half way across another? Can you picture it in your head? Use the interactivity to check your visualisation.
Angle to Chord
problem

Angle to Chord

Age
14 to 16
Challenge level
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Weekly Problem 23 - 2008
A triangle has been drawn inside this circle. Can you find the length of the chord it forms?
Oh so Circular
problem

Oh so Circular

Age
14 to 16
Challenge level
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The diagram shows two circles and four equal semi-circular arcs. The area of the inner shaded circle is 1. What is the area of the outer circle?