Two concentric circles are of diameters 30 cm and 18 cm. Find the length of the chord of the larger circle which touches the smaller circle.
In the diagram AB is the chord touching the smaller circle. We have the right angled triangle OO'B
By Pythagoras theorem
Now since the chord of the larger circle which touches the smaller circle is bisected at the point of contact
We have
AB= 2 × 24= 48 cm
So ans is 18 cm.