Question

u = 3i+2j
v=5i-j
a) find the angle between u and v
b) find the component of u along v
c) find proj_v u

Answer 1

@jim_thompson5910 I did part a but it came out wrong o.o

Answer 2

Angle: cos(theta)= (u*v)/|u||v|

Answer 3

(u*v) = 17 right?

Answer 4

u dot v should be 13

Answer 5

you lost a negative sign

Answer 6

hrm. Yeah I added 2 instead of subtracting it.

Answer 7

|u| = sq13 ?

Answer 8

yep

Answer 9

how about |v|

Answer 10

|v| = sq26

Answer 11

correct

Answer 12

so then
cos(theta) = 13/(13 sq2)

Answer 13

yep

Answer 14

theta = 45

Answer 15

good

Answer 16

ah k, it was just that 13

Answer 17

component of u along v would be 2.54?

Answer 18

sorry got distracted

Answer 19

let me check

Answer 20

I'm getting 2.5495097567964

Answer 21

did you get about the same?

Answer 22

mhm!

Answer 23

Sorry, I didn't see you had replied.

Answer 24

that's ok I didn't see it earlier too

Answer 25

did you figure out part c)?

Answer 26

Yep I got
5/2i - 1/2 j

Answer 27

I got <2.5, -0.5> which is the exact same

Answer 28

Fantastic :)
the form you wrote it in is probably better haha

Answer 29

either way works

Answer 30

oki! thanks :)