I have a set of x,y coordinates spanning the entire northern hemisphere of Mars, and I want to see how many of them fall within 10° of the edges of a given shapefile (polygon). Is there a way I can quickly edit the shapefile to create a version with the boundaries extended by 10°, or is there a way to calculate the intersection of my existing files to account for this 10°? Since the shapes are irregular it would be time consuming to manually extend the boundaries by creating new shapes.