Задача 34797 8. Найти [m]\mathrm{pr}_{\vec{c}}...

vk154799216

2019-03-22 12:23:39

8. Найти [m]\mathrm{pr}_{\vec{c}} \vec{b}[/m], если [m]\vec{b} = (1;5;-3)[/m], [m]\vec{c} = (-2;1;2)[/m].

sova

2019-03-22 12:32:20

★

пр_(vector{c})vector{b}=vector{b}*vector{c}/|vector{c}|


vector{b}*vector{c}=1*(-2)+5*1+(-3)*2=-3

|vector{c}|=sqrt((-2)^2+1^2+2^2)=sqrt(9)=3

[b]пр_(vector{c})vector{b}=-3/3=-1[/b]