RADII is the correct answer to the crossword clue 'Lines on a Pie Chart, e.g.' RADII are lines that divide a circle into sections, and are commonly used in pie charts to represent data. Pie charts are a type of graph that are used to visually represent data, with each section of the chart representing a different value. The RADII of a pie chart are the lines that divide the chart into sections, allowing viewers to easily compare the values represented by each section.