Decagons (b)

THINGS TO DO

You should have ten obtuse Isotiles, if possible five of each colour.

You can make another decagon yourself, using only obtuse Isotiles like the pair on the left. You will have five pairs like this rhombus.

Your shape will have all sides equal, but not all angles equal. It will be a star shape, a concave decagon.

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

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