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There are 2 NRICH Mathematical resources connected to Non-Euclidean geometry, you may find related items under 3D geometry, shape and space.
Broad Topics > 3D geometry, shape and space > Non-Euclidean geometryThis 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.
This article (the first of two) contains ideas for investigations. Space-time, the curvature of space and topology are introduced with some fascinating problems to explore.