Circle properties and circle theorems

There are 50 NRICH Mathematical resources connected to Circle properties and circle theorems
Tied up
problem

Tied up

Age
14 to 16
Challenge level
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How much of the field can the animals graze?
Sports Equipment
problem

Sports Equipment

Age
7 to 11
Challenge level
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If these balls are put on a line with each ball touching the one in front and the one behind, which arrangement makes the shortest line of balls?
Perfect Eclipse
problem

Perfect Eclipse

Age
14 to 16
Challenge level
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Use trigonometry to determine whether solar eclipses on earth can be perfect.
Cyclic Quadrilaterals
problem

Cyclic Quadrilaterals

Age
11 to 16
Challenge level
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Draw some quadrilaterals on a 9-point circle and work out the angles. Is there a theorem?
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.
circles in quadrilaterals
problem

circles in quadrilaterals

Age
14 to 16
Challenge level
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Explore when it is possible to construct a circle which just touches all four sides of a quadrilateral.
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?
Right angles
problem

Right angles

Age
11 to 14
Challenge level
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Can you make a right-angled triangle on this peg-board by joining up three points round the edge?
Subtended angles
problem

Subtended angles

Age
11 to 14
Challenge level
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What is the relationship between the angle at the centre and the angles at the circumference, for angles which stand on the same arc? Can you prove it?
Triangles in circles
problem

Triangles in circles

Age
11 to 14
Challenge level
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Can you find triangles on a 9-point circle? Can you work out their angles?