NumberPlateBoy
New member
- Joined
- Nov 13, 2007
- Messages
- 1
Given ABC and of rectangle ABCD, find equation of line AD and hence find D
OK, I just want someone to point me in the right direction, not give me the answer.
We have three points, A, B and C, for which we have co-ordinates.
There is an unknown point, D, which forms a rectangle with the other points, ABCD.
The question is to find D by getting the equations for AD and CD.
Now, I can get the equation for CD by:
1) getting gradient for AB
2) as CD is parallel to AB, it will have the same gradient
3) pump co-ordinates for C into y=mx + c using gradient for AB, and therefore get equation for CD
BUT, how do I get the eqation for AD? Do i have to use some trig?
A: (4,9)
B: (3,7)
c: (-3,10)
PLEASE don't give me the equation or the co-ordinates of D, I just want some clues about how to do it.
Thanks
M
OK, I just want someone to point me in the right direction, not give me the answer.
We have three points, A, B and C, for which we have co-ordinates.
There is an unknown point, D, which forms a rectangle with the other points, ABCD.
The question is to find D by getting the equations for AD and CD.
Now, I can get the equation for CD by:
1) getting gradient for AB
2) as CD is parallel to AB, it will have the same gradient
3) pump co-ordinates for C into y=mx + c using gradient for AB, and therefore get equation for CD
BUT, how do I get the eqation for AD? Do i have to use some trig?
A: (4,9)
B: (3,7)
c: (-3,10)
PLEASE don't give me the equation or the co-ordinates of D, I just want some clues about how to do it.
Thanks
M
