mohon bantuannya nya

Yg no 4 & 5 gk tauu yaa ;)

[tex]2.a+2b-3c\\ (1,2,3)+(10,8,-2)-(12,-3,3) =(-1,13,-2)\\ \\ 3.4AB=\\ (4,12,24)\\ \\ 4.\frac {AP}{BP}=\frac {3}{1}\\ AP=3BP\\ P-A=3(P-B)\\ P-A=3P-3B\\\ 2P=3B-A\\ P=\frac {3B-A}{2}\\ P=\frac {3(1,0,2)-(1,4,6)}{2}\\ P=\frac {(3,0,6)-(1,4,6)}{2}\\ P=\frac {(2,-4,0)}{2}\\ P=(1,-2,0)\\ PC=C-P\\ PC=(2,-1,5)-(1,-2,0)\\ PC=(1,1,5)\\ \\ 5.PR=R-P\\ PR=(-1,0,2)-(0,1,4)\\ PR=(-1,-1,-2)\\ RQ=Q-R\\ RQ=(2,-3,2)-(-1,0,2)\\ RQ=(3,-3,0)\\ PR.RQ=|PR|.|RQ|.Cos\theta\\ [/tex]
[tex](-1,-1,-2).(3,-3,0)=\sqrt {(-1)^{2}+(-1)^{2}+(-2)^{2}}.\sqrt {3^2+(-3)^{2}+0^{2}}\\ (-1).(3)+(-1).(-3)+(-2).(0)=\sqrt {1+1+4}.\sqrt {9+9+0}Cos\theta\\ -3+3+0=\sqrt {6}.\sqrt{18}.cos\ \textless \ PRQ\\ 0=\sqrt{6}.\sqrt {18}cos\ \textless \ PQR\\ Cos\theta=0\\ \theta=90[/tex]