How do u find the cross product of (10.0825, 20.6723, 0) and (38.1541, 10.2234, 0) respectively (x, y, z)?

Question

please explain how it's done

Answer 1

you dont?

Answer 2

Hi,
My favorite method is to use a matrix. Let's assume vectors u and v. Then: (The dots are only to maintain spaces.)
u x v =| i......j......k|
..........|u1...u2...u3|
..........|v1...v2....v3|

u x v =| i....................j............k|
..........|10.0825...20.6723......0|
..........|38.1541... 10.2234.....0|

Now, it's obvious that the "i" and "j' components are zero. (The cofactors are zero.) So, we solve for the "k" component.
u x v = k..|10.0825...20.6723|
...............||38.1541... 10.2234|
=k (103.0774305-788.7330014)
I'll leave that for your to plug into your calculator.


If you find a case whee the some of the factors are not obviously zero, you might want to look into finding the determinant using the diagonal process (works only for a 3 x 3) which some people find easier to use.

FE

Answer 3

cross products are tricky....i would recommend reading your book or checking out thsi website http://en.wikipedia.org/wiki/Cross_product

but for thsi particular situation you have ...

in the xdirection: 20.6723*0-10.2234*0=0
in the ydirection: -(10.0825*0-38.1541*0)=0
in teh zdirection: 10.0825*10.2234-38.1541*20.6723=-685.655

so in vector coordinates : 0i +0j -685.655k