(a) Show that = A sin kx is a solution to Eq. (40.3) if k = 2mE/h....

(a) Show that ψ = A sin kx is a solution to Eq. (40.3) if k = √2mE/h.
(b) Explain why this is an acceptable wave function for a particle in a box with rigid walls at x = 0 and x = L only if k is an integer multiple of π/L.