$(2)3.$ Resolva em $C$ a equa$$o

$cosz=sinz$

$(2)4.$ Calcule o integral complexo

$o{\displaystyle \underset{|z-1|=2}{\overset{\phantom{}}{}}}\frac{1}{(z^2+4{)}^2}dz$

$(3)5.$ Determine a solu$$o da equa$$o diferencial

$(x^2+y^2)y^{\text{'}}=xy$