Asking this question again,help me please

[tex]r(1) = (2 \: .1 \: . \frac{2}{3} )[/tex]
[tex]r(0) = (0 \: .0 \: .0)[/tex]
[tex] \gamma r =( 2 \: .1 \: . \frac{2}{3} )[/tex]
[tex]l = \sqrt{2 {}^{2} + 1 {}^{2} + \frac{4}{9} } [/tex]
[tex]l = \sqrt{4 + 1 + \frac{4}{9} } [/tex]
[tex]l = \sqrt{ \frac{36 + 9 + 4}{9} } [/tex]
[tex]l = \sqrt{ \frac{49}{9} } = \frac{7}{9} [/tex]
(I'm not sure of my answer tho)
Normally I'd see a plus sign between the x,y and z values of the r(t) equation, so im assuming these represent the x,y,z coordinates in terms of t.
So i calculated ∆r(t) and found the length of the equation using the formula for length