Length of an Arrow: Examples

Example

Find the length of the arrow joining the point \(P(4,-1,11)\) to the point \(Q(-2,6,4)\) in \(\RNrSpc{3}\).

Solution

The length of the arrow \(\Arrow{P}{Q}\) is the distance from \(P\) to \(Q\):

\(\Length{\Arrow{P}{Q}}\)\(=\)\(\Dstnc{P}{Q}\)
\(\)\(=\)\(\sqrt{(-2-4)^2+(6-(-1))^2+(4-11)^2}\)
\(\)\(=\)\(\sqrt{36+49+49}\)
\(\)\(=\)\(\sqrt{134}\)

Example

Find the length of the arrow joining the point \(A(1,3,0,5)\) to the point \(B(2,1,-2,4)\) in \(\RNrSpc{4}\).

Solution

The length of the arrow \(\Arrow{A}{B}\) is the distance from \(A\) to \(B\):

\(\Length{\Arrow{A}{B}}\)\(=\)\(\Dstnc{A}{B}\)
\(\)\(=\)\(\sqrt{(2-1)^2 + (1-3)^2 + ((-2)-0)^2 + (4-5)^2 }\)
\(\)\(=\)\(\sqrt{1 + 4 + 4 + 1}\)
\(\)\(=\)\(\sqrt{10}\)