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'Squirty' printed from  Show menu  Using a ruler and compass
only it is possible to fit a square into any triangle so that
one side of the square rests on one side of the triangle and the
other two vertices of the square touch the other two sides of
the triangle:   Square inscribed in a triangle   How is this
possible?  Prove why this works.  It is easy to draw a square
ABCD with BC on the base PR of the triangle and the vertex D on
the side PQ   Small square drawn in left-hand corner of the
triangle   What happens to the point A as you enlarge the
square? The interactivity may help.  This text is usually
replaced by the Flash movie.