Answer:
radius = 10
Explanation:
As AB is the diameter of the circle, the angle ACB inscribes an arc of 180 degrees, so it is a 90 degrees angle, then the triangle ACB is a right triangle, with hypotenusa AB.
We can find the length of the diameter AB using the Pythagoras' theorem:
AB^2 = CA^2 + CB^2
AB^2 = 12^2 + 16^2 = 400
AB = 20
The radius of the circle is half the diameter, so the radius is 20 / 2 = 10