Is line m perpendicular to line n?

In the rectangular coordinate system, lines m and n intersect at the origin. Is line m perpendicular to line n?

(1) Line n passes through the point (-a, -a), where a 0, and line m has a slope of -1.

(2) The product of the slope of line m and the slope of line n is -1.


1) Is obviously sufficient.

2) Say

Line M : y=0,5x
Line N : y=-2x

Product of both slope = -1

But these are NOT perpendicular...

Am I drunk?

Thanks,

Regards,

David

** And obviously if it's m=x and n=-x, it yields -1 as well and the answer would be that they're perpendicular, thus since it's a maybe, it wouldn't be sufficient... **