- #1

- 8

- 0

## Homework Statement

||

**V**|| = 2

||

**W**|| = 3

angle between vectors = 120 degrees

**V**(dot)

**W**= -3

Find ||2

**V**+

**W**||

## Homework Equations

Cos120 =

**V**(dot)

**W**/ ||

**V**|| ||

**W**||

**V**(dot)

**V**= ||

**V**|| ^2

**W**(dot)

**W**= ||

**W**|| ^2

## The Attempt at a Solution

instead of solving for ||2

**V**+

**W**||

i instead try to solve for ||2

**V**+

**W**|| ^2

||(2

**V**+

**W**)(2

**V**+

**W**)||

= 4

**V**(dot)

**V**+ 4

**V**(dot)

**W**+

**W**(dot)

**W**

=|| 4(2) + 4(-3) + 3||

i add these up and get -1

the book has an answer of 13^(1/2)