Answer:
a) 

b) 

c) 

Step-by-step explanation:
The tangent vector is determined as follows:

Part a
The given function for this instance is:

The derivative is calculated as:

The magnitude of the derivative is determined by:

Thus, the tangent vector is found to be:

Finally, for t=4 we find:

Part b
In this case, we have the stated function:

The derivative can be expressed as:

The magnitude for the derivative is calculated as:


Thus, the tangent vector in this case is:

Finally, when t=4 we find:

Part c
Here, we have the corresponding function stated:

The derivative is stated as:

The magnitude for the derived value is calculated as:


Therefore, we conclude the tangent vector here:

And for the case when t=4, we get:
