# Homework Help: Vector help! advanced biochem

1. Feb 9, 2013

### organgeatom

1. The problem statement, all variables and given/known data
I cannot find other sources to help me with this problem set, I have A B and C vectors defined by: A (2,1,1) B(1,-1,0), C(-1,1,-1)
From these I have a list of questions and some I am stuck on are:each of these are vectors with an arrow above it
1. |A| + |B| this I did as √ax^2 +ay^2 +az^2 + √the same for B
2. |A + B| but how do i do this, what is the difference between these?

3. A + B

4. 3C

5. A dot (B X C)

8. What is the angle between A and B, A and C, and B and C? in radians use pi

id appreciate any help!!

2. Feb 9, 2013

### NemoReally

Have a look at this website http://algebra.nipissingu.ca/tutorials/vectors.html ... I just picked it at random after googling and it seems to cover your questions. Do you have lecture notes or recommended texts?

You are correct in how to solve question 1, question 2 is similar but first you have to add the 2 vectors together, component by component then get the magnitude of the resultant vector ... in fact, solve question 3 before solving question 2.

A scalar multiplying a vector acts equally on all of the vector's components.

You need to look up the "dot" or "scalar" product and the cross product of two vectors to answer 5. Once you know what the dot and cross products are, and how they are defined (eg, a.b = |a| |b| cos(θ), where θ is the angle between a and b), then you should be able to rearrange the equation to get the angle.

Last edited: Feb 9, 2013
3. Feb 9, 2013

### SteamKing

Staff Emeritus
Website address omitted from Nemo's post.

4. Feb 9, 2013

Oops!