You are Here: Home >< A-levels

# Edexcel C4 June 2012 Vectors Q8 C)

Announcements Posted on
TSR's new app is coming! Sign up here to try it first >> 17-10-2016
1. Hi, I'm stuck on this vectors question:

8c) The point c has position vector (3i+12j+3k)

The point P lies on l. Given that vector CP is perpendicular to l,
find the position vector of point P.

And other information I've got before this is
A (10i+2j+3k)
B (8i+3j+4k)
vector eqn of line l = (10,2,3)+λ(-2,1,1)

i tried exam solutions but i didn't understand what he was trying to explain, it seemed too long winded
2. From the looks of it you'd have to sub in P as (10-2s)i, (2+s)j, (3+s)k, and use the fact that you know cp is perp to l so the dot matrix of PC and the (-2s,s,s) =0, from there you just rearrange to find s and sub it into the equation of P. Idk if that's correct or if it helps but I think that's how it's done. GL
edit: it's *(-2,1,1) -- not (-2s,s,s)
3. (Original post by sdfvhgsrbf)
From the looks of it you'd have to sub in P as (10-2s)i, (2+s)j, (3+s)k, and use the fact that you know cp is perp to l so the dot matrix of PC and the (-2s,s,s) =0, from there you just rearrange to find s and sub it into the equation of P. Idk if that's correct or if it helps but I think that's how it's done. GL
edit: it's *(-2,1,1) -- not (-2s,s,s)

Thankyouuu, you're a star i'll give it a whirl

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: June 22, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### How does exam reform affect you?

From GCSE to A level, it's all changing

Poll

## All the essentials

### Student life: what to expect

What it's really like going to uni

### Essay expert

Learn to write like a pro with our ultimate essay guide.

### Create a study plan

Get your head around what you need to do and when with the study planner tool.

### Resources by subject

Everything from mind maps to class notes.

### Study tips from A* students

Students who got top grades in their A-levels share their secrets