It is given that figure KLMN is a parallelogram. The property of parallelogram is that the opposite pair of sides is always parallel. This means the slope of opposite lines is the same. Only under this condition the lines can be parallel. For the slope of lines to be the same the angle they make should be equal as slope is defined as tangent of the angle.
Therefore, we can conclude that for a parallelogram, the opposite pair of angles will always be the same.
So < M = < K
