Question

Determine whether the vectors u and v are parallel, orthogonal, or neither.

u = <7, -4>, v = <-28, 16>

Answer 1

@pizza12

Answer 2

@wio @ganeshie8 @TuringTest @dan815

Answer 3

I think parallel

Answer 4

how'd you figure that out?

Answer 5

I divided the numbers together

Answer 6

u.v=0 if orthogonal
uXV=0 if parallel

Answer 7

u.v=|U||V|cos theta
|u x v|= |U| |V| sin theta

when they are orthogonal cos (90)=0
when they are parallel sin(0)=0

Answer 8

well yeah I know that rule but I don't know the steps on how to calculate it unless its orthogonal...and I know it isn't orthogonal because it doesn't end up being 0 in the end

Answer 9

if u=k*v

Answer 10

then u know they are parallel

Answer 11

take cross product
\[u=-7i+4j,v=-28i+16j\]

Answer 12

u = <7, -4>, v = <-28, 16>
v=-4*(u)

Answer 13

therefore both u and v are vetors with same slope

Answer 14

just of different length

Answer 15

also given a vector u=<a,b>
slope of u=b/a

Answer 16

slope of u=-4/7
slope of v=16/-28=4/-7=-4/7

Answer 17

oh ok I think I forgot to write this part down in my notes:/
and I have one more question I don't understand I got wrong with the law of sines...
Two triangles can be formed with the given information. Use the Law of Sines to solve the triangles.

A = 56°, a = 16, b = 17
I keep getting -.5130898.... and I entered sin^-1 (16sin(56))/17)...what did I do wrong?

Answer 18

nvm ill post this in another question:) thanks for all your help guys:)