Question

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

u = <8, 7>, v = <9, 7>

Answer 1

I am sorry but I do not understand this question.

Answer 2

@youarestupid
-8.3°

1.7°

3.3°

13.3°
Those are the possible answers, but I want to know how to find the angle between the vectors in the question

Answer 3

I do not understand how to solve.

Answer 4

oh

Answer 5

is it multiple choice?

Answer 6

Form equation lab

Answer 7

do you know the formula for the "dot product"?

Answer 8

@youarestupid yes I posted the 4 possible answers
@SGREBORN how do I do that?
@phi Yes I multiply the left number for each vector, than the right, and add them together. right?

Answer 9

oh thanks that makes a lot easier

Answer 10

@youarestupid No problem dude, I just need to understand this stuff :)

Answer 11

3.3

Answer 12

i think

Answer 13

@youarestupid thanks, but can you explain how you came to that conclusion?

Answer 14

yes, but there is a 2nd definition
See http://www.khanacademy.org/science/physics/electricity-and-magnetism/v/the-dot-product
for details

but

\[ x \cdot y = |x| |y| cos\theta \]

Answer 15

Which means that 3.3 is right @phi

Answer 16

to find cos theta you need the magnitude (length) of each vector.
did you find the lengths of both vectors?

Answer 17

@phi how do you find the magnitude with that information?

Answer 18

one way
for u = <8, 7>

think of this as