Decagons (c)

THINGS TO DO

You should have six acute and two obtuse Isotiles.

You can make another ten sided star, in a shape which is often called a pentagram. First use three Isotiles to make a pentagon. You have done this before. Now fit each of the five sides with an acute Isotile, point outwards.

Again your shape will have all sides equal, but not all angles equal, so another a concave decagon. Notice that this time it has only needed 8 Isotiles to make a decagon.

Work out the sum of all ten angles of this shape.

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