Question: PLOT(...) Trying to use Display



I need some help on a problem which seems simple...

I'm doing as follows:

restart; with(LinearAlgebra); with(plots):

II[C] := proc (delta) options operator, arrow; 230/(84192.96489-230*cos(delta)+(-1)*4128.950345*sin(delta)) end proc

(sorry for the formatting)

plot(II[C](delta), delta = -Pi .. Pi)

(This works just fine and produces a nice plot, then I continue)

f1 := plot(II[C](delta), delta = -Pi .. Pi)

(This doesn't work! But gives me this result)


What have I done wrong?
Therefore I can't include it into a display command and add together with other plots!


Plz help me quick.

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