Question

find a * b

Answer 1

a=5i+7j, b=-4i+3j

Answer 2

how do i get rid of i and j? .-.

Answer 3

:/ @ikram002p

Answer 4

is it cross product of dot product ?

Answer 5

-20i and 21j. yes. but how do you get rid of i and j?

Answer 6

im asking is it cross product of dot product ? :P

Answer 7

\(\large \begin{array}{llll}
a=&5i+7j& b=&-4i+3j\\
&(5,7)&&(4,3)\\
&<5,7>&&<4,3>
\end{array}\)

Answer 8

hmm missed the minus there =) \(\large \begin{array}{rrrllll}
a=&5i+7j& b=&-4i+3j\\
&(5,7)&&(-4,3)\\
&<5,7>&&<-4,3>
\end{array}\)

Answer 9

I'm afraid to say... ikram002p is right... is it cross or dot product?

your sign there is rather ambiguous =)

Answer 10

.-. idk it just has a big dot but i got yelled at before on here for assuming it was dot product because of that :P so you tel me c:

Answer 11

hint: ".-. idk it just has a big \(\large dot\) "

Answer 12

\(\bullet \) = dot product

\(\large \mathbb \times \) = cross product

Answer 13

wow big dot :P

Answer 14

@lovelyharmonics lolzu know what dot product is xD

Answer 15

/).(\ i forgot who but on one of my question someone just said that the dot was for multiplication

Answer 16

and no. but im assuming joe did cross product

Answer 17

<x1,y1> ∙ <x2,y2 >=x1x2+y1y2 :D

Answer 18

\(\large ( a_1i + b_1 j) \bullet ( a_2 i + b_2 j ) = a_1a
_2 + b_1 b_2\)

Answer 19

and notice that dot product is just a NUMBER.

Answer 20

wait what 0.0

Answer 21

multiply i components
multiply j components
add them

Answer 22

so.... (5i+7j) dot (-4i+3j)
and i already said -20i+21j but how do i add them .-. they have different variables

Answer 23

\(\large ( 5i + 7j) \bullet ( -4 i + 3 j ) = (5)(-4) + (7)(3) \)

Answer 24

simplify, and you're done !

Answer 25

oh so it +1

Answer 26

i,j are not variables they are direction vectors :D
u should understand that :-\

Answer 27

yep, btw i and j are perpendicular unit vectors :

i.i = 1
j.j = 1
i.j = 0

Answer 28

yay c: eveyones equal now