In the following four cases, let P be the initial (starting) point and Q the ending point. Compute d = the distance from P to Q, x and y. Give your answer in exact form; eg. 2 is an exact answer, whereas 1.41 is an approximation of 2.

(a) P = (0,0), Q = (1,1).

(b) P = (2,1), Q = (1, 1).

(c) P = (1,2), Q = (4, 1).

(d) P = (1,2), Q = (1 + 3t,3 + t), where t is a constant.