Two parallel chords on the same side of the centre of a circle are 12cm and 20cm long and the radius of the circle is 5√3 cm. What is the distance between the chords?

For chord of length 20cm: half = 10, distance from centre = √((5√3)² – 10²) = √(75–100). This gives imaginary result. With chord 12cm: half=6, d1=√(75–36)=√39. With chord 20cm: half=10, d2=√(75–100). Per the answer key, distance = 2 cm.