Wolfram mathematica Wolfram Mathematics出现绘图错误怎么办

我想画出这个等式

Plot[Tan[\[Alpha] Sqrt[\[Beta]^2 - 1]] == ( 0.2 Sqrt[1 - k^2 \[Beta]^2])/Sqrt[\[Beta]^2 - 1], k = 0.75, {{\[Alpha], 0, 1.4}, {\[Beta], 0, 17}}]

但是我得到了这个错误 “预期选项（而不是{{[Alpha]，0,1.4}，{[Beta]，0,17}）\ 超出“绘图”中的位置2，选项必须是规则或规则列表

ContourPlot[
 {Tan[α Sqrt[β^2 - 1]] == (0.2 Sqrt[1 - k^2 β^2])/Sqrt[β^2 - 1], k = 0.75},
 {α, 0, 1.4}, {β, 0, 17}, PlotRange -> {Automatic, {1, 1.5}},
 FrameLabel -> Automatic, BaseStyle -> 14]

比如说

k = 0.75;
sol = FullSimplify[NSolve[
   Tan[α Sqrt[β^2 - 1]] == (0.2 Sqrt[1 - k^2 β^2])/Sqrt[β^2 - 1], α]];

当β为1.25时

sol /. β -> 1.25

使用解决方案进行绘图

sol

expr = sol[[1, 1, 2]];
out = Cases[Table[{expr, β}, {β, 1, 1.5, 0.001}], {_Real, _}];
ListPlot[out, Frame -> True, FrameLabel -> {"α", "β"}, BaseStyle -> 14]

比如说

k = 0.75;
sol = FullSimplify[NSolve[
   Tan[α Sqrt[β^2 - 1]] == (0.2 Sqrt[1 - k^2 β^2])/Sqrt[β^2 - 1], α]];

当β为1.25时

sol /. β -> 1.25

使用解决方案进行绘图

sol

expr = sol[[1, 1, 2]];
out = Cases[Table[{expr, β}, {β, 1, 1.5, 0.001}], {_Real, _}];
ListPlot[out, Frame -> True, FrameLabel -> {"α", "β"}, BaseStyle -> 14]