- [Maximum mark: 9]
The point A has coordinates (1, 2, 1) and the point B has coordinates (3, 5, 2).
(a) Find AB. [2]
Triangle ABC is right‑angled with its right angle at B. The point C has coordinates (2, 8, k).
(b) Find the value of k. [4]
(c) Calculate the size of BÂC. [3]