Microsoft Excel 2010 has the ability to smooth the line between data points on a graph to create a curved graph. However, you do not see this option when you create a graph using the standard templates. The option to smooth the line on a graph only appears when you access the graph's "Format Data Series" menu. Use this menu to convert an existing line graph in Excel to a curved graph.
Launch Excel 2010. Click the green "File" tab in the upper-left corner of the screen, and then click "Open." Double-click the spreadsheet file that you want to add a graph to.
Click and drag the mouse pointer across the letters at the top of the spreadsheet corresponding with the columns containing the data you want to create a curved line graph from.
Click the "Insert" tab at the top of the screen, and then click the "Line" button in the "Charts" section of the toolbar. This displays a menu titled "2-D Line."
Click the "Line" button in the upper-left corner of the "2-D Line" menu. This creates a straight line graph and inserts it in an open area of the spreadsheet.
Right-click the line in the center of the graph. When you click the correct place, Excel displays a box around each data point on the graph. Select "Format Data Series" on the context menu. Excel displays a new window titled "Format Data Series."
Click the "Line Style" heading on the left side of the window.
Click to place a check in the box labeled "Smoothed Line."
Click the "Close" button. Excel 2010 changes the straight line graph to a curved graph.