Question

Find the angle between the given vectors to the nearest tenth of a degree.

u = <-5, -4>, v = <-4, -3>

Answer 1

that formula
cos A = .....

Answer 2

\[\cos \theta = \frac{ u + v }{ u \times v }\]

Answer 3

yes yes :)

Answer 4

Its odd though, when I try to apply it - it doesn't seem to come out properly. For instance, I do -5 multiplied by -4 which gives me 20. -4 times -3 which gives me 12, I add those together and get 32 on the numerator.

Answer 5

Then on the denominator, I'm stuck because in an example it tells me to square root u and v.

Answer 6

but its like
u1v1 +u2v1 /

Answer 7

Aaaaaah.

Answer 8

I was doing it the other way around.

Answer 9

wait
i will use the equation?

Answer 10

\[\frac{ u_1v_1+u_2v_2 }{ \sqrt{u_1^2u_2^2}.\sqrt{v_1^2v_2^2} }\]

Answer 11

Okay, so you don't do u1 and u2, you do u1 and v1..

Answer 12

yeah we do that

Answer 13

we do them

Answer 14

and we get cos = something something

Answer 15

and from that we find the answer

Answer 16

Yes, but that is where I'm stuck. I get the numbers at the bottom but when I try to figure it out my calculator says Domain Error.

Answer 17

hah
wait i will solve

Answer 18

top is 32

Answer 19

I see..
The answer choices however are: -9.1 degrees, 1.8 degrees, 0.9 degrees, and 11.8 degrees.

Answer 20

nooo >_> i did it wrong
i didnt square the bot terms

Answer 21

okay wait

Answer 22

25+16 =41
root 41
16+9 = 25
root 25

Answer 23

so cos A = 32/root 41 * root 25
thats cos A = 0.999
A= arc cos 0.999
thats 2.5 .-. which is not an option

Answer 24

Actually, I got 1.789910768 on my calculator which rounds off to 1.8 so you did fantastic aajugdar~!

Answer 25

Thank you so much for helping me!

Answer 26

yeahhh when i added 0.999512
gave me the same ^^

Answer 27

Thank you for helping me, I hope that you have a great day. ^^

Answer 28

welcome :)
its night here though

Answer 29

Whoops. Well, have a good night then. xD