What happens to the perimeter of triangle ABC as the two smaller
circles change size and roll around inside the bigger circle?
Stage: 4 Challenge Level:
Slice the tetrahedron in two with a cut through the line $b$ and
one of the equal edges. The perpendiculars are very important
because of what you need to find the volume of a pyramid. You now
have two identical pyramids like this:
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. More information on many of our other activities
can be found here.