x Turn on thread page Beta
 You are Here: Home >< Maths

# traingle question and simultaneous equations question watch

1. Got these two questions wrong: Attachment 511157511159

Here's my working:[attach]5.1115751115951116e+23[/attach] Attachment 511157511159511200
Attached Images

2. (Original post by Airess3)
...
not sure what your working out for q8 is, but you need to take the dot product of the vectors (equate it to zero because perpendicular and form two simultaneous equations in a,b)
3. (Original post by Zacken)
not sure what your working out for q8 is, but you need to take the dot product of the vectors (equate it to zero because perpendicular and form two simultaneous equations in a,b)
In my working, I already equated them to zero, I just moved the value of k over to the other side, hence the -1. I still don't know how to do it. And question 6.
4. question 6
Let u=AB and v=AC
u=(1-2,-7-4,3-(-6))
then

(to be continued.....by you)
5. (Original post by Airess3)
x
for question 8 in your workings you are using i, j which isn't correct

After dot product only the coefficients of each component remain;

Notice how i, j, k are gone.

which is just simultaneous equations, if you need help with those, here is an example, http://www.thestudentroom.co.uk/show...5&postcount=11

Edit: your mistake on Q8 was going from line 4 to line 5 of your workings, check that again
6. (Original post by depymak)
question 6
Let u=AB and v=AC
u=(1-2,-7-4,3-(-6))
then

(to be continued.....by you)
I did that in the working posted above. I don't understand why it was wrong.
7. sorry, I didn't see it.
(Original post by Airess3)
I did that in the working posted above. I don't understand why it was wrong.
8. [QUOTE=Airess3;63263905]x[QUOTE]

using is incorrect, you need to use instead, the direction does matter

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:
Updated: March 9, 2016
Today on TSR

### Loughborough better than Cambridge

Loughborough at number 1

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams