we know that
if the dilated circle passes through the point (4, 0)
so
the new radius is the distance from the origin to point (4,0)
d=√[(4-0)²+0²]-----> d=√16------> d=4 units
the new radius is 4 units
original radius is 1 units
[new radius]=[scale]*[original radius]
scale=new radius/original radius-----> scale=4/1-----> 4
the answer is
the scale factor of dilation is 4
