## wampominater one year ago Find the angle between the given vectors to the nearest tenth of a degree. u = <-5, -4>, v = <-4, -3>

1. wampominater

so far, i have followed the formula $\cos(\theta) = \frac{ u*v }{\left| v \right| \left| u \right| }$ and i have gotten 1, but that isnt an answer choice...

2. wampominater

and then when I take the arc cos of 1, I get 0, which is not a choice

3. anonymous

$$\huge |u| = \sqrt{(-5)^2+(-4)^2} = \sqrt{41}$$ $$\huge |v| = \sqrt{(-4)^2+(-3)^2} = 5$$ That what you have for |v| and |u| ?

4. wampominater

yeah, i believe i know what i did wrong now though

5. anonymous

you sure? I can work it out if you want

6. wampominater

well, i think that its because i rounded the denom to 32

7. wampominater

but sure, if you want to help me do it just to make sure, thatd be great! :)

8. wampominater

so i got approx 1.8 when i didnt round the denominator

9. anonymous

We should have $$\huge \cos(\theta) = \frac{ u*v }{\left| v \right| \left| u \right| }$$ $$\huge \cos(\theta) = \frac{ 32}{\left| 5 \right| \left| \sqrt{41} \right| } = .99951 = 1.78 degrees$$ That is what I got.

10. wampominater

awesome, that is what i got too, thank you for the help!

11. anonymous

YW!!!