The family of circles x2+(y−b)2=b2 depends on the non–zero real parameter b.
a. (i) Derive dxdy in terms of x, y and b.
b. (ii) Determine the values of b for which at least one point on the circle has a tangent slope equal to 3.
c. (iii) For each admissible value of b, find the coordinates of all points where the tangent has slope 3.