If you have a function for the curve, plot it using the plot command and not the scatterplot command. You can also plot the tangent line with the plot command and your data with the scatterplot command.
I'm having trouble with some plotting in Maple. I have a set of data plotted along with a fitted curve using the scatter plot command. I'm trying to plot a line tangent to a point on the curve in the same plot. I've tried a bunch of stuff but nothing seems to work. Is there something that I'm missing, or might there be a better approach altogether?