1 zz1 2zxzzx 1 zz 0 in the region 0 lt x lt ir 0 lt y

Question

Show that

Z(x, y) = ln(sin y/sin x)

is a solution to the minimal surface equation.

(1 + Z)Z1 + 2ZXZZX + (1 + Z)Z = 0, in the region 0 < x < ir, 0 < y < pi. What happens on the boundary of this region? Suppose we consider a constant multiple of Z(x, y) ? is it still a solution of the PDE?