Answer:
x = 6
Explanation:
The radius in this case measures; 20/2 = 10 since the diameter is 20.
The chord measuring 16 units has been bisected, hence each portion measures 8 units.
We now apply Pythagoras theorem since we are dealing with a right angled triangle with 2 given sides;
x^2 = 10^2 - 8^2
x^2 = 36
x = 6