Prove that the area of a circular path of uniform width h surrounding a circular region of radius r is pi h (2r+h)

Answer 1

A(r) = πr^2
A(r+h) = π(r+h)^2

now subtract.

Answer 2

Prove that the area of circular path of uniform width h surrounding a circular region at radius r is pi h 2r+h

Answer 3

2pieh (2r+h)