1) Ina plane there are two families of lines Y = x + r, Y = -x + r , where r belongs to {0,1,2,3,4}. The number of squares of diagonols of length 2 formed by the lines is :-
(a) 9 (b) 16 (c) 25 (d) None of these
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2 Answers
62if it is a square, you should chose two lines which are parallel to each other at a distance of √2
so if r=4, there is 1 line given by r=2,
same if r=3 and r=2, the line is given by r=1, and 0 respectively
This holds for both set of parallel lines
hence the answer is 3^2=9
