Stage: 5 Challenge Level: 
Two trees 20 metres and 30 metres long, lean across a passageway between two vertical walls. They cross at a point 8 metres above the ground. What is the distance between the foot of the trees?
Circles. Pythagoras' theorem. Long problems. Other equations. Mathematical reasoning & proof. Scale factors. Newton Raphson Method. Approximate solution by numerical methods.. Similarity. Pythagorean triples.
Published January 2000.
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