Question

Determine the projection of the first vector on the second.
a=[6,-1], b=[11,5]

Answer 1

I used the formula \[((a \times b)\div(b \times b)) \times b\]

Answer 2

the vector projection? or its magnitude?

Answer 3

MY final answer was (5.94,-1)
Vector projection I think.

Answer 4

Answer is [4.6,2.1]

Answer 5

Correct answer.

Answer 6

b.a
---- b
|b|^2


since the naming is a bit backwards

Answer 7

So I'm using the right formula?

Answer 8

yes
\[|a| cos(t)\frac{b}{|b|}\]

cos * unit

Answer 9

So how am I getting the wrong answer?

Answer 10

Heres my work

Answer 11

a=[6,-1] ; 36 1 = sqrt(37)
b=[11,5] ; 121 25 = sqrt(146)
------
66-5 = 61

61
---- <11,5>
146

Answer 12

=(((6,-1)*(11,5))/((11,5)(11,5)))(11,5)
=((6*11,-1,5)/(11*11,5*5))(11,5)
=((66,-5)/(121,25))(11,5)
=(0.54,0.2)(11,5)
=(5.94,-1)

Answer 13

Wait. What are you doing in your steps? IT's a little confusing.

Answer 14

finding my parts

the under is a.b

and to each side is the magnitudes of each

Answer 15

magnitude is: square add and sqrt

Answer 16

Your lingo is confusing.

Answer 17

=((66,-5)/(121,25))(11,5)

=(0.54,0.2)(11,5) <---- .54,0.2 what is that?

=(5.94,-1)

Answer 18

both parts of the vector is positive; and your scalar is positive; how do you end up with a - anything in the end result?

Answer 19

0.54 is 66/121
0.2 is -5/25

Answer 20

ok, but what is that?

\[\frac{66-5}{121+25}=\frac{61}{146}\]

Answer 21

youre fine up till you decide to invent your own thing there

Answer 22

I dunno. What is that? I didn't write that. I wrote ((66,-5)/(121,25))

Answer 23

i know what you wrote; and you wrote some magical fantasy spell that has nothing to do with finding what you started out to find in the first place

Answer 24

66 and -5 are components of a dot product; you combine them to get a single value .... as defined by a dot product.

the magnitude of b is a single value, not some ordered pair ...

Answer 25

But the final answer is [4.6,2.1]...

Answer 26

According to da txtbook.

Answer 27

yes it is; which is:
\[\frac{61}{146}<11,5>\implies <\frac{61(11)}{146},\frac{61(5)}{146}>\]

Answer 28

this decimal out to about 4.6 and 2.1

Answer 29

Ok. Lemme try it out. I guess you shoulddo more importantthings as I write it down.

Answer 30

well, i DO have to urinate :)

Answer 31

I'm done. Thank you very much, amistre64.

Answer 32

youre welcome :)