TO FIND CENTRE OF AN ARC

Method 1:

1. Draw an Arc AB

2. Draw any two chords on arc as CD, EF

3. Draw Bisector to CD, 

4. Draw Bisector to EF, 

5. Extend these bisectors until they meet at a point.

6. Mark this point as 'O'.

7. This point 'O' is the centre of the arc.