Answer:
Therefore the unit tangent vector is

Therefore the parametric form is



Step-by-step explanation:
Given 
To find the unit tangent we need to find r'(t) and |r'(t)|.
The unit tangent vector 

Differentiate with respect to t


Therefore the unit tangent vector is
.......(1)
The parametrization equation
x(t) = t² , y(t)=t and z(t) 
Given point is 
Therefore,
,
and 
Then t =4.
The unit tangent vector at t= 4
[Putting t = 4 in equation (1)]


The parametric equation is
x= x₁+at
y =y₁+bt
z=z₁+ct
Here a=8 , b=1 and c=0
,
and 
Therefore the parametric form is


