# Homework Help: Vector Problem - is this even solvable?

1. Sep 10, 2011

### The_Chromer

1. The problem statement, all variables and given/known data
[PLAIN]http://img703.imageshack.us/img703/8599/physicsks.png [Broken]

2. Relevant equations
I'm considering cross product and dot product rules, yet I don't know where to begin with this one.

3. The attempt at a solution
I have two pages of scratch paper that is littered with failed attempts to solve the problem.

-There are no values for a or b given.
-Is there even enough information to solve these problems?

Last edited by a moderator: May 5, 2017
2. Sep 10, 2011

### wukunlin

this is basically a set of 2X2 simultaneous equation, which you can do by seperating the two components of each vector

3. Sep 10, 2011

### SteamKing

Staff Emeritus
Hint: a and b are constants which multiply the vectors A and B, respectively. There is no implied dot or cross product in the problem statement as shown.

4. Sep 10, 2011

### The_Chromer

I think I'm on the right track... thanks guys. Can you confirm if this is heading in the correct direction?

a<81,-73>+b<-79,49>+<60,85>=<0,0>

So,

81a-79b+60=0
-73a+49b+85=0

?

5. Sep 10, 2011

### wukunlin

yup :)

6. Sep 10, 2011

### The_Chromer

These numbers are ugly... mind sticking around until I work it out? :)

7. Sep 10, 2011

### The_Chromer

Still haven't figured it out :/

Last edited: Sep 10, 2011
8. Sep 10, 2011

### wukunlin

do you have to solve it by hand? or are you allowed to use calculators/computers?

9. Sep 10, 2011

### The_Chromer

Even if I solve it, I still think there's something going wrong... I'll use a computer. I just tried doing it with matrices, lol.

10. Sep 10, 2011

### wukunlin

you can always substitute your answers back into the question and see if the identity holds, faster and simpler than rechecking all your steps

11. Sep 10, 2011

### The_Chromer

You're right - I have new values for a and b

a=5.520297
b=6.489422

Pretty sure I got it! Thank you for your help!

12. Sep 10, 2011