4. Find 33 0: Or and Dy if is a function of r and y, and defined implicitly by = ln(r:)-:tan(ry). [6 marks] 5. Let 'ecos (gr), with p rlu (ry:). qcos (ry) and r2tan (y). By using the chain rule, find, when r-y=:=1. Dy [3 marks] SSCE 1993. Differentiations Differentiations of Inverse Functions d d 11, & constant. de d d -1 - dr VI 1 ta 112 d dz d d -1 1120 1 |>1. d -1 de d tan 4 02-2 of 1 de el d we d 1 wztanz. tanh