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Is the diagram correct for both solutions?
Xtra
Age 14 to 18
Challenge Level 
Why do this problem?
There are several different ways of solving this problem. It is a good example to bring home the point that, to be an expert problem solver, and to understand a piece of mathematics, it is not enough to find an answer. One should ask oneself "Have I used the best method?". This problem can be solved using trig formulae and the cosine rule but it can be solved more straightforwardly using only Pythagoras theorem.Possible approach
Challenge the class to find different methods of solution.Key question
How do we interpret the two solutions?Is the diagram correct for both solutions?
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