Stage: 4 Challenge Level: 
The diagram shows three squares on the sides of a triangle $ABC$.
Their areas are respectively 18 000, 20 000 and 26 000 square centimetres.
If the squares are joined, three more triangular areas are enclosed. What is the area of this convex hexagon?
Pythagoras' theorem. Cosine. Sine. Circles. Perimeters. Long problems. Scale factors. Stage 5 needs dealing with. Complex numbers. Area.
Published May 1998.
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