linear help

[davidle_10]

Stuck on this question:
ABCD is a parallelogram,lettered anticlockwise, such that A and C are the points (-1,5) and (5,1) respectively.
a) Find the coordinates of the midpoint AC.
b) Given that BD is parallel to the line whose equation is y+5x=2, find the equation of BD.
c) Given that BC is perpendicular to AC, find:
i) the equation of BC
ii) the coordinates of B
iii) the coordinates of C

I have done all the answers apart for c)ii and c)iii.

This is what I have so far:
a) (2,3)
b) y=-5x+13
c)i 2y-3x=13

[brightsky]

Can you roughly draw the parallelogram on a cartesian plane. BD has a positive gradient on mine..

[davidle_10]

sorry but it didn't come with a graph.
but the coordinates of B and D are: (3,-2) and (1,8).
I just don't know how to find these points

[davidle_10]

Brightsky. I can tell you that the gradient of BD is negative because it is parallel to the equation
y+5x=2 or y=-5x+2.

[cindyy]

i have a positive gradient for BD on mine too :S

[cindyy]

& dont you already have to co ordinates for c ? (5, 1)

[samuch]

me three

[cipherpol]

i have a positive gradient for BD on mine too :S

BD is negative because it is parallel to the line , which can be rearranged into

for c.ii)
[1]
[2]

Solve simultaneously

[brightsky]

He's already got the coordinates for B. I think...

but the coordinates of B and D are: (3,-2) and (1,8).
I just don't know how to find these points

Me is bemused by the paradox?

[the.watchman]

He must have used BoB!!!

[cindyy]

i have a positive gradient for BD on mine too :S

BD is negative because it is parallel to the line , which can be rearranged into

yeah i understand that, it just when i draw my parrelelogram, BD is positive. lol

He must have used BoB!!!

LOll gotta love bob

[davidle_10]

Lol, I used Bob. But I just needed to find out how to solve B and D. I have already found the coordinates of B and D by using simultaneous equations. Thanx for the replies.