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'Triangles All Around' printed from http://nrich.maths.org/
Students will need to apply what they know about angles in circles and triangles in order to calculate the angles in each triangle they draw. The problem encourages them to be clear about what they do know and what they can work out from it.
If working on paper rather than using the interactivity, pupils may find it helpful to print these sheets off:
Sheet of four-peg
Sheet of six-peg
Sheet of eight-peg
This problem offers an opportunity for pupils to work in a systematic way, using their knowledge of the properties of triangles. A useful discussion about which triangles are the same and which are different could be encouraged.