# A pair of perpendicular vectors

1. Oct 15, 2012

### ArcherofScience

A pair of perpendicular vectors....

1. The problem statement, all variables and given/known data
This thread contains 2 questions that are similar.

A pair of 482.5 N vectors are perpendicular.
What is the magnitude of their resultant?

Two vectors of magnitudes 24 N and 31.1 N
act at right angles to each other.
What is the magnitude of their resultant?

2. Relevant equations

for the first one, what do u exactly do? just find the resultant and that's it? is their a magnitude sign such as north of east or something? do i have to find theta?

for the second one, what does it mean it acts of right angles ot each other? is it just the resultant or what?

3. The attempt at a solution

1st: 482.5 ^2 + 48.5^2= r^2
232806.25 + 232806.25 = r^2
√465612.50=r^2
r= 682.358 <----does it need a positive or negative sign?

2nd: 24^2 + 31.1^2 = r^2
576 + 967.21 = r^2
√1543.21= r^2
r= 39.3219 <--- did I even solve this right?

2. Oct 15, 2012

### Dick

Re: A pair of perpendicular vectors....

"acting at right angles" or "perpendicular" mean the same thing. And it means you can apply the pythagorean theorem, just like you did. And again, the word "magnitude" means you don't have to worry about signs. I get a slightly different number from you on the second one. Did you punch a calculator key wrong? And don't forget to specify units in your answer.

3. Oct 15, 2012

### ArcherofScience

Re: A pair of perpendicular vectors....

oh yeah i just realized my mistake, its 39.2837 i believe. but thanks for your help ! i understand it i believe a bit more, just the way it was worded had me a bit pressured.

4. Oct 15, 2012

### Dick

Re: A pair of perpendicular vectors....

You are maybe worrying a bit more than you need to. And yes, I get 39.2837N. Don't forget the units!