1, the distance between the island and the nearest point P on the coastline is 2km, which proves that the island, point P and stop point form a right triangle. Point P- stop point-town-|-. | - 。 | 。 Island map: in Rt△XPD ∠XPD=π/2, and the distance traveled by this person is the root sign (x? +2? )Km； The walking distance of this person is (12-x) km; The time it takes this man to fly a spaceship is the root sign [(x? +2? )/3]h； The walking time of this person is [(12-x)/5] h; t=[(x？ +2? )/3]+[( 12-x)/5]；