Paper 3, Section I, B

Complex Methods
Part IB, 2021

Find the value of AA for which the function

ϕ(x,y)=xcoshysinx+Aysinhycosx\phi(x, y)=x \cosh y \sin x+A y \sinh y \cos x

satisfies Laplace's equation. For this value of AA, find a complex analytic function of which ϕ\phi is the real part.