In a circle, two chords \(UU'\) and \(VV'\) are drawn perpendicular to a diameter \(ST\). Determine that the segment \(MM'\) joining the midpoints of the chords \(UV\) and \(U'V'\) is perpendicular to \(ST\).
 
Proof:
 
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Let \(O\) be the centre of the circle.
 
Since, the chords \(UU'\) and \(VV'\) are the two chords perpendicular to \(ST\).
 
This implies, the chords \(UU'\) and \(VV'\) are .
 
Now, consider the chords \(UV\) and \(U'V'\).
 
By theorem,
 
Therefore, \(OM⊥\) .
 
That is, \(∠OMU = \angle OMV =\)\(^°\)    ......(1)
 
Also, \(OM'⊥ \).
 
Therefore, \(\angle OM'V' = \angle OM'U'\) \(^°\)    ......(2)
 
From (1) and (2), we can say that, the chords \(UV\) and \(U'V'\) are .
 
Thus, we can say that, \(M\), \(M'\) and \(O\) are .
 
\(ST\) passes through . [Given]
 
Therefore, the line \(MM'\) passes through the centre \(O\) and is perpendicular to \(ST\).
 
Hence, proved.