# Calculate the following quantity? Let a= (2, 0,-1), b=(-1, 2,-1), c=(i - j -3k): Calculate the following?

Let a= (2, 0,-1), b=(-1, 2,-1), c=(i - j -3k):

Calculate the following quantity ............ I a - c I

### 2 Answers

- 8 years agoBest answer
First calculate the vector, a - c, being very careful to watch the negative signs: (2-1, 0- (-1), -1-(-3)) = (1,1,2). To find the square of the magnitude of this vector, |a-c|^2, use the pythagorean theorem (or, equivalently, just "dot" the vector with itself), (1, 1, 2) * (1, 1, 2) = 1^2 + 1^2 + 2^2 = 1 + 1 + 4 = 6. Then take the square root of the magnitude to find |a-c| = sqrt(6).

To reinforce your understanding, I've searched and found a webpage and a video tutorial that address problems similar to this one, and I thought they might be helpful to you. I've listed them below.

As always, if you need more help, please clarify where you are in the process and what's giving you trouble. I'd be more than happy to continue to assist.

Source(s): http://www.netcomuk.co.uk/~jenolive/vect5.html http://www.youtube.com/watch?v=6GoMXuE1FOw