1. A length of chord 12cm long is 8 cm from the centre of the circle

(a)find the radius of the circle
(b) calculate the length of another chord which is 7 cm from the centre of the circle

Draw a diagram. You will see that

(a) r^2 = 6^2 + 8^2
(b) (x/2)^2 + 7^2 = 10^2