This article outlines the underlying axioms of spherical geometry giving a simple proof that the sum of the angles of a triangle on the surface of a unit sphere is equal to pi plus the area of the triangle.
Stage: 4 Challenge Level:
What are the most efficient proportions for a tin of paint?
"Efficient" could mean different things from different points of
view - maybe start by trying to minimise the amount of material
needed to make a tin with that volume.
What is the best diameter and height for a tin that contains $1$
litre of paint?
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.