Only One Question Probability

Note that this is equivalent to sampling a point uniformly at random from the unit
square [0, 1]
2
. Find the probability of the following:
(a) |X − 1
2
| ≤ 1
4
,
(b) |X − Y| < 1
2
,
(c) max{X,Y} < 1
2
,
(d) X
2 Y
2 < 1
4