To create a chart you need some data. What data do you have / wish to use? What level of accuracy do you want at interpolated points? Will you be reading the values off by eye or do you want Excel to do the lookup for you? In the latter case, the formula will be working from the data table and the chart is merely illustrative.
Thank you, yes I do have the data to use , now I need to know the way to construct the charts I want, the inbuilt charts in excel I'm failing to use them to that task
Broadly speaking, I think you need one or more scatter charts with lines but no markers. For accuracy the line width should be 1pt for on-screen reading and a pale coloured grid with major and minor gridlines should allow you to read the values off the chart to 3 s.f. The series description can be inserted as a label at the top or bottom of the curve (rather than using a legend). Data specific to a particular case could be shown by cross-wires in a contrasting colour superposed on the chart.
