Foot of perpendicular

  • Thread starter MMCS
  • Start date
  • #1
MMCS
151
0
I apologise in advance for an extremely trivial question, i am returning to brush up on some basic maths and can't seem to arrive at the answer

Find the coordinates of the foot of the perpendicular from the point A with coordinates (-5,5) to the line 10x+2y-3= 0

1.) gradient of original line -10/2, gradient of intercepting line 1/5
2.) equation of intercepting line y-5 = 1/5(x+1) *5
3.)5y-25 = x+1 re-arranging gives 5y-x = 26
4.) solve simultaneously -10x-50y=-260 ( *-10 )
10x+2y=3

-48y=-257

y=5.354
Substituting y into either equation
x= -0.7708

From the program i know these answers arnt correct

Any pointers would be appreciated,

Thanks
 

Answers and Replies

  • #2
36,710
8,711
I apologise in advance for an extremely trivial question, i am returning to brush up on some basic maths and can't seem to arrive at the answer

Find the coordinates of the foot of the perpendicular from the point A with coordinates (-5,5) to the line 10x+2y-3= 0

1.) gradient of original line -10/2, gradient of intercepting line 1/5
2.) equation of intercepting line y-5 = 1/5(x+1) *5
Mistake above. The known point on the intersecting line is (-5, 5), so the equation of this line would be y - 5 = (1/5)(x - (-5))

Why do you have "*5" on the right side of your equation?
3.)5y-25 = x+1 re-arranging gives 5y-x = 26
4.) solve simultaneously -10x-50y=-260 ( *-10 )
10x+2y=3

-48y=-257

y=5.354
Substituting y into either equation
x= -0.7708

From the program i know these answers arnt correct

Any pointers would be appreciated,

Thanks
 
  • #3
MMCS
151
0
Hi,

I had the *5 to remove the fraction, don't know how i ended up with the 1 on the right hand side. That sorted it. Thanks for spotting that, such a silly mistake. Wouldnt think id been staring at it for half an hour. Probably suggests i need some sleep :bugeye:
 
  • #4
ehild
Homework Helper
15,543
1,915
I apologise in advance for an extremely trivial question, i am returning to brush up on some basic maths and can't seem to arrive at the answer

Find the coordinates of the foot of the perpendicular from the point A with coordinates (-5,5) to the line 10x+2y-3= 0

1.) gradient of original line -10/2, gradient of intercepting line 1/5
2.) equation of intercepting line y-5 = 1/5(x+1) *5

Check the red part.

ehild
 
  • #5
36,710
8,711
Hi,

I had the *5 to remove the fraction
If you multiply one side by 5, you need to also multiply the other side by the same number. Maybe you did this, but it doesn't show in your work.

It's best to start a new line when you do this kind of operation.
, don't know how i ended up with the 1 on the right hand side. That sorted it. Thanks for spotting that, such a silly mistake. Wouldnt think id been staring at it for half an hour. Probably suggests i need some sleep :bugeye:
 

Suggested for: Foot of perpendicular

  • Last Post
Replies
13
Views
587
  • Last Post
Replies
8
Views
595
  • Last Post
Replies
6
Views
763
Replies
3
Views
2K
  • Last Post
Replies
6
Views
1K
Replies
10
Views
1K
Replies
3
Views
2K
Replies
4
Views
2K
Replies
1
Views
303
  • Last Post
Replies
3
Views
4K
Top