Answer:
answers are given below
Explanation:
1.
Circumference =

Where 2r = Diameter
Hence
Circumference =
2.
No there is no such circle in which relationship between Radius and Diameter can be represented without
.
This is because while deriving the relation the angle measurement ts taken into consideration and the angle are measured in radians i.e. in terms of
not degrees.
3. We can not determine the exact circumference because
is a rational number and but its value is approximately taken from
and
is an irrational number