Would the following information and working help?
Part (a):
The circle of intersection will be perpendicular to the axis the spheres are centred on as both spheres centre on the 𝑧-axis, one at (0, 0, 0) and the other at (0, 0, 5).
The sphere of intersection between the two spheres will be parallel to the 𝑥𝑦-plane.
Part (b):
![1675516918259.png](/data/attachments/37/37652-8c010481763e0c6e0d5e616bf98478bb.jpg)