Passage: The aircraft's main design elements date to early 1965, from the internal Northrop project N-300. The N-300 was itself derived from the F-5E, and features a longer fuselage, small leading-edge root extensions (LERX), and more powerful GE15-J1A1 turbojets, rated at 9,000 lbf (40 kN) each. The wing was slightly elevated to increase ordnance flexibility. The N-300 further evolved into the P-530 Cobra, which uses 13,000 lbf (58 kN) GE15-J1A5 engines, with a very small .25 bypass ratio leading to the nickname "leaky turbojet". The bypass effectively was only a cooling stream for the rear of the engine, allowing the engine bay to be constructed of lighter, cheaper materials.The P-530's wing planform and nose section was similar to the F-5, with a trapezoidal shape formed by a sweep of 20° at the quarter-chord line, and an unswept trailing edge, but was over double the area, with 400 sq ft (37 m2) as opposed to 186 sq ft (17.3 m2) of the F-5E. Initially shoulder mounted, the wings were gradually shifted down to the mid position. Its most distinctive new feature were the LERXs that tapered into the fuselage under the cockpit. They enabled maneuvering at angles of attack exceeding 50°, by providing about 50% additional lift. The extensions also trapped airflow under them at high angles of attack, ensuring airflow into the engines. The resemblance to the head of a cobra lead to the adoption of the nickname "Cobra", often unofficially used for the YF-17.

Question: What do the planes design traits come from?
Northrop project N-300