Answer 1

Let the chord be AB = 24 cm
Distance of the chord from the centre O is 5 cm. 
AO is the radius of the circle. 
Perpendicular from the centre of the circle to the chord bisects the chord. 
So, AC = CB
In Δ AOC, 

OC² + AC² = AO²

⇒ 5² + 12² = AO²

⇒ AO² = 25 + 144 = 169

⇒ AO = 13 cm

Thus, the radius of the circle is 13 cm.