Let's see that initially, the figure indicates with equal lines in both angles, that the two angles present in M are congruent and for K must be the same.
Now, An angle bisector is defined as a ray, segment, or line that divides a given angle into two angles of equal measures. As MK is a line that divides an angle of 90 degrees into two congruent angles then MK is an angle bisector.
As we have a square, at each vertex a 90-degree angle is formed then M has a right angle. In conclusion,
-MK is an angle bisector.
-M is the vertex of a pair of congruent angles in the diagram
-K is the vertex of a pair of congruent angles in the diagram
-M is the vertex of a right angle