# Vectors Cambridge Q (1 Viewer)

#### hmim

##### Member

Can someone explain how to do 15b please.

#### hmim

##### Member
Think about how u did A
Here for B externally means that AB : AB extended outside is 2:3 so how would u achieve this?/
Hm, i tried using -2/3-2 AP and then doing OA + AP to find OP but it isn't working

#### hmim

##### Member
So an example would have likely been given in the chapter. Are using the textbook?
hm yeah, but there isn't an explicit working for external division, so I'm a bit confused

#### hmim

##### Member

Can someone show their working for (C) please

I don't really understand what they did here in the worked solutions. Why does it not use AG from part (A) and (B)?

#### synthesisFR

##### Well-Known Member
View attachment 38338

Can someone show their working for (C) please

View attachment 38339
I don't really understand what they did here in the worked solutions. Why does it not use AG from part (A) and (B)?
which part exactly dont u understand. Finding the midpoint?
Using AG would not be a good idea as its just unnecessary, this question doesn't state use part a and b, it asks u to do something else.

#### synthesisFR

##### Well-Known Member
send ur working what uve done so far

#### carrotsss

##### New Member
I can’t write out a worked solution, but another way think about it is purely from a visual vector perspective. What you’re basically doing is adding 1 in the y direction to get to C, and then adding another half in the x and z directions to get to the middle of the 1x1 square. Then it’s just a simple magnitude calculation

#### wizzkids

##### Active Member
The short answer is because parts (a) and (b) are irrelevant to part (c). That's why you can't use (a) or (b) to answer (c).
Here is a partial solution to (c), see if that helps.

#### hmim

##### Member

Yeah, like i got really stuck. i tried following what they did in the example