Answer:
r = 4 units
Explanation:
From the question it is not clear that what you want to ask. But as per me you are interested in finding the radius of the circle.
Since, circle is touching y-axis at has a center (-4, 8) so it's radius will be equal to the x-coordinate.
Here, x - coordinate is - 4
Since radius is a non negative number.
So, r = 4 units