Here's the question you clicked on:
marird15
How can u tell whether these lines are parallel or perpendicular or neither with out graphing? line 1; through (-1,9) and (-6,-6) line 2; through (-7,-23) and (0,-2)
(-1,9) and (-6,-6) : slope =3 (-7,-23) and (0,-2): slope=3 same slope means lines are parallel
how did you figure that out with out graphing?
there is a formula to find the slope of line with 2 points given....
They calculated the slope of each line using \[\Delta y \over \Delta x\] When the slopes are equal to each other (in this case they were both 3) they are parallel. If they were negative reciprocals like one was 3 and the other -1/3. then they would of been perpendicular.
for perpendicular,slopes must be negative inverse
@radar I used that method....sorry for nothing showing my work.
ohhhh. okay i got it. and its okay @RyanL.
@RyanL, good work, I was just trying to assist. I want to explain what a negative reciprocal is, because by the questions being submitted he is going to need to understand that too.
One number is a negative reciprocal of another number if their product is -1.
its alright.. and okay thanks.. again. lol