1. Sep 27, 2006

wtee85

Okay so i need a little help.

Heres the problem.

Find a vector that has the same direction as <-2,4,2> but has length 6. :surprised

So i Did the |v|= Sqrt( A1^2+A2^2+A3^2)= sqrt(24) which is how you begin to find the unit vector with the same direction. I get stumped on how to find it with length 6. The new vector with the same direction would be... <-2/Sqrt(24), 4/Sqrt(24), 2/Sqrt(24)... but.. what about the length of 6..?

Can anybody help me? What do i do with this length of 6? :yuck:

... any help would be awesome!!!!!

2. Sep 27, 2006

Staff: Mentor

Say you scaled the original vector by the same amount in all 3 dimensions. Which way would the scaled vector point?

3. Sep 27, 2006

wtee85

Do you just multiply everything by 6, or in your example by 3?

4. Sep 27, 2006

Hint: what is the manitude of the unit vector?

5. Sep 27, 2006

wtee85

The magnitude of the unit vector is sqrt(24) as i stated above. That is sqrt(24) of the original vector.

6. Sep 27, 2006

wtee85

???? Help?

7. Sep 27, 2006

Hargoth

No, it's one. That's why it is called " unit vector". So what do you have to do to get a vector of length 6 pointing in the same direction?

8. Sep 27, 2006

wtee85

Do u multiply or divide by 6? Im seriously lost as in how to get the new vector which i have found the direction too, to get a length of 6.. im totally lost. I would assume you multiply by 6, thus it would be length of 6?

9. Sep 27, 2006

Hargoth

That's right. Think of it as an stick which is one cm long and pointing in some direction - to get a stick with a length of 6 cm and pointing in the same direction, you have to stick six of these sticks together.

10. Sep 27, 2006

wtee85

Okay so i need to multiply the new vector by 6. That means <a1*6, a2*6,a3*6>? Do u see what i mean?