Three triangles ABC, CBD and ABD (where D is a point on AC) are all
isosceles. Find all the angles. Prove that the ratio of AB to BC is
equal to the golden ratio.
Stage: 5 Challenge Level:
The second part of this question introduces an expression involving
an infinite string of nested square roots but, as forbidding as it
may seem, a little ingenuity is all that is needed to evaluate it.
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