Chapter 4.10, Problem 21E

In calculus the curvature of a curve that is defined by a function y = f(x) is defined as

$\kappa =\frac{y^{″}}{{[1+{(y^{\prime })}^2]}^{3\text{/}2}}$

Find y = f(x) for which κ = 1. [Hint. For simplicity, ignore constants of integration.