A proof without words Nov 23, 2020 Via nRICH: A circle touches the lines OA extended, OB extended and AB where OA and OB are perpendicular. Show that the diameter of the circle is equal to the perimeter of the triangle. $\blacksquare$ A selection of other posts Sep 18, 2019 Ask Uncle Colin: Multiple solutions Feb 23, 2015 Three simple tricks I wish my GCSE students would use Sep 24, 2014 The Maths Police Investigate: IndyRef edition Apr 22, 2013 The Mathematical Ninja's Ten Coolest Numbers subscribe via RSS