Question

For any 2 vectors a,b the cross product "(3a + 2b) x a" is the same vector as:
a) 2a x b
b) 2b x a
c) 3a x b
d) 3b x a
e) 5b x a

Answer 1

is cross product the same as dot product?

Answer 2

i see that they arent.... i was sooo close lol

Answer 3

yeah they aren't the same

Answer 4

is cross priduct orthogonal? they perpendicular to each other then?

Answer 5

yeah

Answer 6

i was just reading up on vectors last night... if 2 vectors are othogonal, they have -1 as the product of their slopes... we wouldnt happen to know the vector quantities would we...

Answer 7

no, the question I asked is really all the information given :(

Answer 8

||a x b ||^2 = ||a||^2 ||b||^2 - (a.b)^2...does that help us any? :)

Answer 9

is that like the law of cosines? o_O

Answer 10

3<xa,ya> + 2<xb,yb>

<3xa+2xb , 3ya + 2yb> right?

lol.....wish I knew

Answer 11

would it be asking this then?

<3xa+2xb , 3ya + 2yb> (x) <xa,yx>

Answer 12

oh perhaps

Answer 13

well actually i think i'd need to add the z-component, since we'd get a 3-D vector

Answer 14

i gots no idea how to add a z component in there ;)

Answer 15

what would 3a x a = ? is it still a vector a multiplied by smtg?

Answer 16

oh wait it would be 0 right o_o

Answer 17

cant recall :) do you know where this mystery vector is supposed to be attached? I got this so far...but I may be wrong.

Answer 18

ohh I figured it out! :) haha. Ok i wasn't sure but there's the property that (3a + 2b) x a = 3a x a + 2b x a
= 0 + 2b x a... omg -_-

Answer 19

thats a nice property to know then ;) good job!

Answer 20

oye our prof never showed it to us :( Lol glad that was actually easy now xD thx for ur help nevertheless :)