Question 363469
a)
{{{drawing(300,300,-1,9,-4,6,grid(1), 
circle(0,0,0.2),circle(2,3,0.2),circle(7,4,0.2),
blue(line(0,0,2,3)),line(2,3,7,4),green(line(0,0,7,4)),
graph(300,300,-1,9,-4,6,0))}}}
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{{{A}}}=({{{2}}},{{{3}}}) :Blue
{{{B}}}=({{{5}}},{{{1}}}) :Black
{{{A+B}}}=({{{2+5}}},{{{3+1}}})=({{{7}}},{{{4}}}) :Green
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b)
{{{F[1]}}}=({{{3}}},{{{-2}}},{{{5}}})
{{{F[2]}}}=({{{-1}}},{{{7}}},{{{-3}}})
{{{F[3]}}}=({{{5}}},{{{-1}}},{{{4}}})
{{{F[4]}}}=({{{0}}},{{{-2}}},{{{3}}})

{{{F[R]}}}={{{F[1]+F[2]+F[3]+F[4]}}}=({{{3-1+5+0}}},{{{-2+7-1-2}}},{{{5-3+4+3}}})=({{{7}}},{{{2}}},{{{9}}})
{{{abs(F[R])=sqrt(7^2+2^2+9^2)=sqrt(49+4+81)=sqrt(134)}}}