Question: No resulting graph

I have some problems about plotting in Maple.

Question1. I have tried to plot this function for different intervals, but there is no resulting graph.


What do you think why this happens?

Question2. plot(1+18*(sinh(9*x-9/2)-sinh(3*x-477/2))^2/(9*cosh(9*x-9/2)+cosh(3*x-477/2))^2,x=-1..1);

The graph of this function is a wierd one. Is there any problem?


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