Question 364633
Find the dot product because,
{{{a*b=abs(a)abs(b)cos(theta)}}}
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{{{a*b=a[1]*b[1]+a[2]*b[2]+a[3]*b[3]}}}
{{{a*b=1(2)+3(1)+(-1)(-1)=2+3+1=highlight(6)}}}
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{{{abs(a)=sqrt(1^2+3^1+(-1)^2)=sqrt(1+9+1)=sqrt(11)}}}
{{{abs(b)=sqrt(2^2+1^2+(-1)^2)=sqrt(4+1+1)=sqrt(6)}}}
{{{cos(theta)=a*b/(abs(a)*abs(b))=6/(sqrt(11)sqrt(6))}}}
{{{cos(theta)=(6*sqrt(66))/66=sqrt(66)/11}}}
{{{cos(theta)=0.7385}}}
{{{highlight(theta=42.4)}}}degrees