(i) With O as centre and any suitable radius, draw arcs to cut AB at points S and T.
(ii) Take radius equal to more than half the length of ST.(iii) With this radius, taking points S and T as centres, draw two arcs which intersect at point P.
(iv) Join OP.(v) Then OP is the perpendicular to AB at O.
(vi) \OP bisects AB, OA = OB.