Stage: 4 Challenge Level: 
The diagonals of a square meet at $O$.
The bisector of angle $OAB$ meets $BO$ and $BC$ at $N$ and $P$ respectively.
The length of $NO$ is $24$.
How long is $PC$?
Area. Similarity. Radius (radii) & diameters. Fractal. Similar triangles. Perimeters. Pythagoras' theorem. Pentagons. Golden ratio. Scale factors.
Published June 2002.
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