The lengths of two parallel chords of a circle are 6 cm and 8 cm. If the smaller chord is at a distance of 4 cm from the centre, what is the distance of the other chord from the centre?
Distance of smaller chord AB from centre of circle = 4 cm
OM = 4 cm
MB = 
= 
= 3 cm
In 
OM2 + MB2 = OB2
(4)2 + (3)2 = OB2
16 + 9 = OB2
OB2 = 25
OB = 5 cm
In 
OD = OB = 5 cm (Radii of same circle)
ND = 
= 
= 4 cm
ON2 + ND2 = OD2
ON2+ (4)2 = (5)2
ON2 = 25 – 16
= 9
ON = 3
SO, distance of bigger chord from circle is 3 cm.
17