my mom
This is literally 3rd grade math. Seriously, I looked it up on my public school system's site. WTF. If it's really your mom, why don't YOU know this? Failing that, are you too fucking retarded to google the terms and click the first fucking link?
>>3
Yeah, I saw that too... and I didn't know whether to facepalm or to raff. Underage b&?
Just in case http://en.wikipedia.org/wiki/Slope Two lines are parallel if and only if their slopes are equal and they are not coincident or if they both are vertical and therefore have undefined slopes. Two lines are perpendicular if the product of their slopes is -1 or one has a slope of 0 (a horizontal line) and the other has an undefined slope (a vertical line).
>>2 almost had it, except for the pathological "infinite slope" case.