This activity helps the student to establish the relationship between two equal chords of a circle and its distance from the centre.

1) Observe the length of CD and EF
2) As you change the length of CD by moving the points either C or D, Observe the lengths of CD and EF
3) Change the position of EF by moving E and note the length of CD and EF
4) From (2) and (3) , how CD is related to EF?
5) Observe ∠OMC and ∠ONE.
6) What can you say about the points M and N?
7) Why?
8) Examine the values of OM and ON as you repeat step (2) or (3)..
9) What can you observe?
10) Change the radius of the circle by moving the position of O
11) Repeat the procedure
12) Note down your observation.
13) Frame the theorem based on your observation.