Thanks for the help, but I'm still kinda confused.
Ok, so the vectors would be:
AB: [0,-8,10] or -8j +10k
AC: [14,-8,14] or 14i - 8i + 14k
To find the moment caused by AC do i simply multiply? 100[0,-8,10]? Or do i have to split up the 100 lb tension into its x y and z components and...