i) Mark any point C on the sheet. Now, by adjusting the compass up to 3 cm and by putting the pointer of compass, draw the circle. It is the required circle of 3 cm radius.
ii) Take any two chords AB and CD in the circle.
iii) Taking A and B as centres and with radius more than half of AB, draw arcs on both sides of AB, intersecting each other at E, F. Join EF which is the perpendicular bisector of AB.
iv) Taking C and D as centres and with radius more than half of CD, draw arcs on both sides of CD, intersecting each other at G and H . Join GH which is the perpendicular bisector of CD.
Now, we find that EF and GH meet at the centre of circle O.