Two straight lines are given at right angles. Since AB = AC, the triangle is an isosceles right-angled triangle. The required equation is of the form
y – 2 = m(x – 1) .....(1)
Substituting the value of m in Eq. (1), we get the required equations. Equation of lines are y – 2 = –7 (x – 1) and y - 2 = 1/7 (x - 1).