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Set Square

A triangle PQR, right angled at P, slides on a horizontal floor with Q and R in contact with perpendicular walls. What is the locus of P?

Fixing It

Age 16 to 18
Challenge Level

Think about angle $APB$.

You might like to use dynamic geometry software to help with this problem. You can download geogebra for free from We have pre-drawn a diagram if this is useful to you.