Basically, the RadChart uses data points, through which the curve runs, and does not support the described chart type by default. However, you can achieve this scenario by manually calculating sufficient number of data points and set them to the chart. You can also use line or spline chart to visualize the data. The difference between these two chart types is that the spline curve is actually an approximation - when the path between two points is calculated, it takes into account their adjacent "outer" points. Have a look at the following online resources for an overview of the Spline Charts:
I hope that this information helps.
the Telerik team
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