Answer:
The radius = 3 units.
Step-by-step explanation:
Ad and AB are both radii of the circle . Let each = r.
Using the Pythagoras theorem:
(r+2)^2 = r^2 + 4^2
r^2 + 4r + 4 = r^2 + 16
4r + 4 = 16
4r = 12
r = 3.
