## anonymous one year ago Identifying parallel and perpendicular lines from coordinates...Help!

1. anonymous

This is the one...

2. anonymous

@Luigi0210

3. anonymous

Do you know how to use this equation to find the slope of a line?$m=\frac{ y_2-y_1 }{ x_2-x_1 }$

4. anonymous

yes

5. anonymous

great. you want to start by using that equation to get the slopes of the three lines

6. anonymous

0/3 for the first one

7. anonymous

I got m = (8 - 2) /(-3 - 0) = 6/(-3) = -2

8. anonymous

Its confusing

9. anonymous

you have to enter the points into the equation|dw:1444407766451:dw|

10. anonymous

oooohh i was doing something else but I understand now

11. anonymous

then that reduces to $m=\frac{ -6 }{ 3 }$ $m=-2$

12. anonymous

yeah so the first one is -2

13. anonymous

yep. try the 2nd one

14. anonymous

8/-4

15. anonymous

yes and what does that reduce to?

16. anonymous

2/1

17. anonymous

-2 actually

18. anonymous

now the third

19. anonymous

ok 8/4 = 2

20. anonymous

yep. ok so the three slopes are line 1 = -2 line 2 = -2 line 3 = 2

21. anonymous

for part b. parallel lines have the same slope, so lines 1 and 2 are parallel perpendicular lines have opposite reciprocal slopes. (like if one line has slope of 2, then the other must have slope of -½.) None of them are like that, so none of the lines are perpendicular

22. anonymous

ok

23. anonymous

@peachpi what about 6/9 , 2/-3 , 3/2

24. anonymous

where did those numbers come from?

25. anonymous

I did this one

26. anonymous

@peachpi

27. anonymous

ok. reduce the first one to 2/3. for the 2nd one, once you're done with the math move the negative sign out front, so it's -2/3. None of them are the same, so none are parallel. 2/3 and -3/2 have different signs, and are reciprocals (aka flipped over). so the lines with those two slope are perpendicular

28. anonymous

oops. the 3/2 is positive, so it's perpendicular to the line with slope of -2/3. That looks like lines 2 and 3 are perpendicular