The answers are derived directly from the provided context of Exercise 11.1 and Example 1. (i) The term 'XY-plane' is explicitly used in Question 4(ii), identifying the plane determined by the x-axis and y-axis. (ii) Example 1 demonstrates that if the distance measured along an axis is zero (e.g., along OY), the corresponding coordinate is zero. For points in the XY-plane, the distance along the Z-axis is zero, resulting in the form (x, y, 0). (iii) Question 3 of Exercise 11.1 lists 8 distinct points and asks to name the octants they lie in, implying that coordinate planes divide the space into eight octants.