Help pls find vector b given a = 5i +j, a dot b = 12, and the angle between a and b is 58 degrees (1 Viewer)

Interdice

Well-Known Member
Joined
Jun 24, 2021
Messages
522
Gender
Male
HSC
2023
All I managed to get out of this is that

cos(58) = 12/(5x + y)
 

Interdice

Well-Known Member
Joined
Jun 24, 2021
Messages
522
Gender
Male
HSC
2023
looking at the answers it is actually b = 3i -3j or b = 1.6i + 4.2j.

NEed some help figuring out how to get to the answers
 

tywebb

dangerman
Joined
Dec 7, 2003
Messages
1,712
Gender
Undisclosed
HSC
N/A
I think we will be doing this:







At this point I think you can solve it but I put the equations in wolframalpha in the following way:

5x+y=12 and cos(58 degrees)=12/sqrt(26x^2+26y^2)

and got this:

wa ans.png
 
Last edited:

Drongoski

Well-Known Member
Joined
Feb 22, 2009
Messages
4,238
Gender
Male
HSC
N/A
I got |b| = 2.618 . . . instead of 4.441 . . ..
With this correction,(multiplying my answers by 4.441/2.618) should end up with roughly the same answer.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top