Each of these solids is made up with 3 squares and a triangle around each vertex. Each has a total of 18 square faces and 8 faces that are equilateral triangles. How many faces, edges and vertices does each solid have?
Triangles to Tetrahedra
Age 11 to 14 Challenge Level:
Think about how the lengths of sides of the triangles are
You could use Polydron (plastic shapes that click
together) to make the models yourself.
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.