What is the resistance of a 100m copper wire with a radius of 0.3
(Resistivity of copper is 1.6 x 10-8 Ωm)

Suppose that f : rn → rm and that a ∈ k, where k is a connected subset of rn . suppose further that for each x ∈ k there exists a δx > 0 such that f(x) = f(y) for all y ∈ bδx (x). prove that f is constant on k; that is, f(x) = f(a) for all x ∈ k