National Parks
National Monuments
National Historical Parks, Memorials, and Battlefields
National Recreation Areas, Seashores and Trails
Other Preserves and Protected Areas
... trinomial of the form x2 + 2xy + y2. Since "2xy" in this case is (b/a)x, we must have y = b/(2a), so we add the square of b/(2a) to both sides, ...