Question

Помогите с векторами пожалуйста ​

Answer 1

4) cos(ac)=(ac)/|a||c|=(xa*xc+ya*yc+za*zc)/sqrt(xa^2+ya^2+za^2)sqrt(xc^2+yc^2+zc^2
cos(ac)=(3*6+2*2+1*(-4))/sqrt(9+4+1)sqrt(36+4+16)=18/sqrt(14*56)=18/28=9/14
5) sqrt(9+4+1)+sqrt(36+4+16)=sqrt(14)+sqrt(56)=3sqrt(14)
6) b*c=(4*6+(-1)*2+2*(-4))=24-2-8=14