Question

The line Q passes through the points (-10,-2) and (-8,-8).

The line R passes through the points (1,2) and (10,a).

The lines Q and R are perpendicular.

Find a.

Thanks.

Answer 1

slope of line Q = (-8+2)/(-8+10) = -6/2 = -3
slope of line R = (a-2)/(10-1) = (a-2)/9

but they are perpendicular, so
(a-2)/9 = -1/3

continue