Kara and Lindsey both hike in separate directions from their campsite, with Kara hiking straight to the east and Lindsey hiking straight north. At 2:00 p. m., Kara hiked twice as far to the east as Lindsey hiked to the north. At 2:30 p. m., Kara had covered another mile, while Lindsey had covered another half of a mile. If x represents Lindsey's distance, in miles, from the campsite at 2:00 p. m., what function could be used to represent the area of the triangular region formed by the girls' locations and the campsite at 2:30 p. m.?