Question 117110

by definition, the lines through the points are perpendicular if their slopes are negative reciprocals.

a. {{{y=6x-7}}}..........this line has slope {{{6}}}
b. {{{y=1/6x+7}}}...........this line has slope {{{1/6}}}
c. {{{y=-1/6x+7}}}...........this line has slope {{{-1/6}}}
d. {{{y=1/6x-7}}}...........this line has slope {{{1/6}}}

since only {{{-1/6}}} is negative reciprocal of {{{6}}}, lines {{{a}}} and {{{c}}} are perpendicular.


*[invoke solve_by_graphing 6, 1, 7, -1/6, 1, -7]