If (– 4, 5) is one vertex and 7x – y + 8 = 0 is one diagonal of a square, then the equation of the other diagonal is
The vertex (−4, 5) is not on \(7x - y + 8 = 0\) (since \(-28 - 5 + 8 \ne 0\)), so it must lie on the other diagonal.
The diagonals of a square are perpendicular. The given diagonal has slope 7, so the other has slope \(-\frac{1}{7}\): it has the form \(x + 7y = k\).
Through (−4, 5): \(k = -4 + 35 = 31\).
Other diagonal: \(x + 7y = 31\)
Answer: (B)
Reinforce your conceptual grasp with related questions from MAH MCA CET 2015:
Take timed full-length mock tests with authentic question distributions, negative marking (+12/-3 in Math), and instant All India Rank calculation.
Start Free Mock Test Series →