Question

помогите очень срочно!!!

Answer 1

$overline{p}=(1,2,3),quad overline{q}=(6,4,-2)\\2overline{p}=(2,4,6),quad frac{1}{2}overline{q}=(3,2,-1)\\2overline{p}cdot frac{1}{2}overline{q}=6+8-6=8\\|2overline{p}|=sqrt{4+16+36}=sqrt{56}=2sqrt{14}\\|frac{1}{2}overline{q}|=sqrt{9+4+1}=sqrt{14}\\cos alpha =frac{8}{2sqrt{14}cdot sqrt{14}}=frac{8}{2cdot 14}= frac{2}{7}$