Question

In a plane there are two families of lines y $=$ x +r, y $=$ -x + r, where $r\in 0,1,2,3,4$. The number of squares of diagonals of the length 2 units formed by the lines is

• A. 9
• B. 16
• C. 25
• D. 36

Answer 1

The correct option is A 9

Length of diagonal is $2$ units means length of side is $\sqrt{2}$ units i.e. the two parallel lines must be alternate. i.e. no. of ways $=3\times 3=$ 9