Regular polygons and circles

There are 118 NRICH Mathematical resources connected to Regular polygons and circles
Cube Paths
problem

Cube Paths

Age
11 to 14
Challenge level
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Given a 2 by 2 by 2 skeletal cube with one route `down' the cube. How many routes are there from A to B?
Circle Packing
problem

Circle Packing

Age
14 to 16
Challenge level
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Equal circles can be arranged so that each circle touches four or six others. What percentage of the plane is covered by circles in each packing pattern? ...
Star Gazing
problem

Star Gazing

Age
14 to 16
Challenge level
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Find the ratio of the outer shaded area to the inner area for a six pointed star and an eight pointed star.
From all corners
problem

From all corners

Age
14 to 16
Challenge level
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Straight lines are drawn from each corner of a square to the mid points of the opposite sides. Express the area of the octagon that is formed at the centre as a fraction of the area of the square.
Square Pegs
problem

Square Pegs

Age
11 to 14
Challenge level
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Which is a better fit, a square peg in a round hole or a round peg in a square hole?
Hexagon Transformations
problem

Hexagon Transformations

Age
7 to 11
Challenge level
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Can you cut a regular hexagon into two pieces to make a parallelogram? Try cutting it into three pieces to make a rhombus!
Escriptions
problem

Escriptions

Age
16 to 18
Challenge level
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For any right-angled triangle find the radii of the three escribed circles touching the sides of the triangle externally.
Retracircles
problem

Retracircles

Age
16 to 18
Challenge level
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Four circles all touch each other and a circumscribing circle. Find the ratios of the radii and prove that joining 3 centres gives a 3-4-5 triangle.
Get Cross
problem

Get Cross

Age
14 to 16
Challenge level
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A white cross is placed symmetrically in a red disc with the central square of side length sqrt 2 and the arms of the cross of length 1 unit. What is the area of the disc still showing?
Fitting In
problem

Fitting In

Age
14 to 16
Challenge level
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The largest square which fits into a circle is ABCD and EFGH is a square with G and H on the line CD and E and F on the circumference of the circle. Show that AB = 5EF. Similarly the largest equilateral triangle which fits into a circle is LMN and PQR is an equilateral triangle with P and Q on the line LM and R on the circumference of the circle. Show that LM = 3PQ