Plus r CA, again, is 3i minus 12 K,

crossed with FAY, which is all in the Y direction.

So that's FAY in the J. And I have RCD, so

plus RCD to go from R from C to D, walking from tail to

head as we did in my earlier course. We've got 3 in the X

direction, so 3 i. Plus 4j minus

12k crossed with

the given force of 100i minus 100k.

Plus, the last force is from r from C to B.

So that's nothing in the x direction, 4 in the j direction, and minus

12 in the k direction. Crossed with FBX, which is all

in the i direction, equals

zero. Now, if you do those cross products and

the mathematics. What you'll come out with for your

moment equation is 3FAY in the K direction,

plus 12 FAY in the i direction,

minus 12. FAX in the j

direction, plus 300j,

minus 400k, minus 400i,

minus 1200j. Minus

4 FBXk,

minus 12 FBXj.

Now, if you couldn't do those cross products and

come up with that result, again, I think you

need to go back and review, the skills that

we learned in my earlier course, introduction to engineering mechanics.

And so once we have that the question is what we, what do we do now?

And think about that.