You can
put this solution on YOUR website!Imagine the side that is

laying flat
on a table. The side that is

is hinged
at one end of the

. It is free to swing
in a plane that is perpendicular to the table.
-----------------------------------
If you lay it alongside the

side, the
difference is

, so

is one limit.
-----------------------------------
As I swing the

side I must stop before
the distance from the free end of

and
the unhinged end of

equals

,
because

must be the shortest side
-----------------------------------
So, the limits are

Hope this isn't confusing