PlotRegionHighlighter-package
                        Creates an envelope that surrounds a set of
                        points plotted in two dimensions
arcAngle                The counterclockwise arc of two points relative
                        to a third
centersLineSegmentIntersections
                        Determine if a line intersects one or more line
                        segments
createCircle            A set of points defining a circle or an arc
drawArc                 Compute the points on an arc starting with the
                        coordinates of the starting and ending points
                        relative to the circle center
envelopeArea_and_Perimeter
                        Calculate the area and perimeter of the
                        envelope
findExteriorTangents    Determine the set of tangents to a pair of
                        circles that do not intersect other circles or
                        pass between circles
generateEnvelope        Generate an minimum-perimeter envelope that
                        surrounds a set of points in a graph
tangentLine             Compute the coefficients for the line tangent
                        to two circles
