Answer:
[tex]\approx 9.0\:\mathrm{units}[/tex]
Step-by-step explanation:
The magnitude of 3D vector [tex]\vec{v}[/tex] can be given by the following:
[tex]| \overline{v}| =\sqrt{{v_x}^2+{v_y}^2+{v_z}^2}[/tex]
Plugging in given values, we have:
[tex]| \overline{v}|=\sqrt{3^2+7.2^2+4.5^2},\\| \overline{v}| \approx \fbox{$9.0\:\mathrm{units}$}[/tex].