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Wire Cages

Age 7 to 14
Challenge Level Yellow star
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  • Getting Started
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 You may wish to look here at a 2D task which could be explored before this 3D task.  
 


Wire cages are used to contain large rocks in some building projects.


Here is a small version of a 2 by 3 by 4 wire cage cuboid, made with plastic straws.


 
 
 

We can see 14 red rods of length 2 units, 12 blue rods of length 3 units and 10 green rods of length 4 units.

For all the challenges below, no rod is allowed to be longer than 6 units and each cage is always a cuboid. 


Challenge 1


The example above of dimensions 2 by 3 by 4 uses exactly 36 rods and has a volume of 24 cube units.

Find all the cages that have a volume of 20 to 25 cube units inclusive and use 40 to 50 rods inclusive.

Challenge 2


The example above of dimensions 2 by 3 by 4 uses exactly 36 rods.

Can you find a cuboid that uses exactly 28 rods?
Can you find all the cuboids that use exactly 28 rods?

 

Challenge 3


Find at least one pair of cuboids of different dimensions, that when constructed: 
- Use exactly 100 rods 
AND
- Have each dimension greater than 2 rods.

This sheet contains a copy of the task.
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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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