Given that

we first differentiate with respect to t to get the tangent vector,
:

At t = 0, the tangent vector is

To get the <em>unit</em> tangent vector, multiply this by 1/(norm of tangent vector) :

Then the unit tangent vector is

Answer:
7.9
Step-by-step explanation:
The mnemonic SOH CAH TOA reminds you of the relationship of the hypotenuse and the side opposite an angle:
... Sin = Opposite/Hypotenuse
For your geometry, this is ...
... sin(21°) = x/22
Multiplying by 22 gives ...
... x = 22·sin(21°) ≈ 7.9
Yogirlnikki sorry i can not see.
643=4x160+n =that is the problem
n=3