Question

Find the angle between the given vectors to the nearest tenth of a degree. u = <2, -4>, v = <3, -8>?

Answer 1

use dot product.

Answer 2

Okay, so
2*3=6
-4*-8= 32
and 6+32
=38?

Answer 3

but thats not one of my answer choices @surry99

Answer 4

My choices are:
3.0°
6.0°
-7.0°
16.0°

Answer 5

dot product says:
u.v = |u||v|cos(theta)

Answer 6

oh, where do you get cos theta thought?

Answer 7

though*

Answer 8

theta is the angle between the vectors by defintion

Answer 9

hmmm, okay.. I don't know how to set that up. U and V are 6 and 32 though, right?

Answer 10

Oh! I just figured it out, nevermind(:

Answer 11

you did the left hand side...u.v
now you need the:
magnitude of u = |u|
magnitude of v = |v|

Answer 12

good

Answer 13

thank you! @surry99

Answer 14

you are welcome!