The sum of the interior angles of a triangle are equal to 180^{o}. To find
the third angle of a triangle when the other two angles are known subtract the number
of degrees in the other two angles from 180^{o}.

Example: How many degrees are in the third angle of a triange whose other two angles
are 40^{o} and 65^{o}? Answer: 180^{o} - 40^{o} -65^{o} =
75^{o}