how to find CENTRE of a circle using a set square not circumference?? answer my previous question plz

We can find the center of a circle using a set square by following the mentioned steps.

Step I: Place the perpendicular vertex on any part on the circumference of the circle.

Step II: Draw rays along the perpendicular sides of set square such that it intersects the circle at A and B.

Step III: Draw the mid point O of AB. Now O is the required center.