Answer: 3.6
We have a diameter of 12 so a radius of 6.
The chord makes a right angle with a different diameter, which bisects the chord, so each piece is 4.8.
x is the remaining leg. Let's write 4.8=4(1.2) and 6=5(1.2) so this is a 3/4/5 right triangle, x= 3(1.2) = 3.6
