# Pls help vectors

Watch
Announcements
#1
Can someone pls help me with section c
0
2 years ago
#2
Couple of ways to approach it, but using the dot product = 0 is probably the easiest.
So D lies on the line and you want to determine the value of the line scalar multiplier which gives the dot product with the line direction as zero.
0
#3
why do we use the product rule?
(Original post by mqb2766)
Couple of ways to approach it, but using the dot product = 0 is probably the easiest.
So D lies on the line and you want to determine the value of the line scalar multiplier which gives the dot product with the line direction as zero.
0
2 years ago
#4
Just imagine a line which does not pass through the origin.
All points a constant distance from the origin lie on a circle (distance r from the origin).
The closest point of a line is therefore when the circle expands just enough so that the line is a tangent to a point on the circle.
That point represents the closest point D and OD is perpendicular to the line direction (zero dot product).
(Original post by IGCSEsurvivor)
why do we use the product rule?
0
#5
I'm sorry I didn't quite get that
(Original post by mqb2766)
Just imagine a line which does not pass through the origin.
All points a constant distance from the origin lie on a circle (distance r from the origin).
The closest point of a line is therefore when the circle expands just enough so that the line is a tangent to a point on the circle.
That point represents the closest point D and OD is perpendicular to the line direction (zero dot product).
0
2 years ago
#6
Which part? The diagram in
is ok, with C = origin in your case.

The line has to be tangential to the circle which represents the distance from the origin and D is the tangent point.

(Original post by IGCSEsurvivor)
I'm sorry I didn't quite get that
0
#7
thanks I got it now
1
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### What support do you need with your UCAS application?

I need help researching unis (21)
14.69%
I need help researching courses (8)
5.59%
I need help with filling out the application form (7)
4.9%
I need help with my personal statement (58)
40.56%
I need help with understanding how to make my application stand out (36)
25.17%
I need help with something else (let us know in the thread!) (3)
2.1%
I'm feeling confident about my application and don't need any help at the moment (10)
6.99%