Series[Cos[x], {x, 0, 7}]

Series[Sin[x], {x, 0, 7}]

Series[Exp[I*x], {x, 0, 7}]

Plot[{Sin[x]^2, 0.5 - 0.5*Cos[2*x]}, {x, 0, 2  Pi}];

<< Calculus`VectorAnalysis`

SetCoordinates[Cartesian[x, y, z]];

hacko = {0, 0, Hz[y]};
Curl[hacko]

rov = Laplacian[hacko][[3]] == 
        I*γ*ω*μ*hacko[[3]]

res = DSolve[rov, Hz[y], y]

Simplify[
        Hz[y] /. res[[1]], {γ > 0, μ > 0, ω > 0}] // 
      N

((7. *(10^86)*7. *(10^86)*4*Pi*(10^(-7))*(10^(-6)))/(15*(10^9)*3600*24*365))

Plot[Exp[x], {x, 0, 200}, PlotRange -> All]

Hres = C2*Exp[-(1 + I)*(y/a)];

Curl[{0, 0, Hz[y]}]

ClearAll[Hz];
Hz[y_] = H0*Exp[-(1 + I)*(y/a)];
Jx[y_] = Curl[{0, 0, Hz[y]}][[1]]

proud = 
      Simplify[m*Integrate[Jx[y], {y, 0, ∞}], {a > 0}]

Ex[y_] = (1/γ) Jx[y]

napeti = Ex[0]*d

impedance = (napeti/proud)