find the centre of circle by construction using only 60-30 setsquares and a pencil

We can construct the centre of a circle using a set square and a pencil by these steps:

1. Place the perpendicular vertex on any part on the circumference of the circle.

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

3. Draw the mid point O of AB. Now O is the required center.