# Require assistance with this vectors question. #1

• Feb 24th 2013, 11:46 PM
kel0021
Require assistance with this vectors question. #1
Attachment 27238
Extremely difficult for me, just started learning about vectors, need a worked solution.
Problem is in the image attached.
• Feb 25th 2013, 02:06 AM
earboth
Re: Require assistance with this vectors question. #1
Quote:

Originally Posted by kel0021
Attachment 27238
Extremely difficult for me, just started learning about vectors, need a worked solution.
Problem is in the image attached.

Use your index finger to do those exercises:

1. Go from A to C: From A to B + from B to C. With vectors:

$\overrightarrow{AC} = \vec a + \vec b$

Since P is the midpoint of AC you'll get:

$\overrightarrow{AP} = \frac12 (\vec a + \vec b)$

2. According the method from #1 you'll get

$\overrightarrow{AQ} = \vec a + \frac12 \cdot \vec b$

3. You "go" from P to Q like: From P to A + from A to Q. With vectors:

$\overrightarrow{PQ} = -\frac12 \cdot ( \vec a + \vec b) + \vec a + \frac12 \cdot \vec b$

$\overrightarrow{PQ} = \frac12 \cdot \vec a$

4. This vector has the same direction as $\vec a$ and half of it's length.