1, let the time be t, and the time coordinate of the enemy ship be (90T, 120). The tracking missile is always aimed at the enemy ship. Missile coordinates (x, y) indicate that the northeast corner of the missile is consistent with the enemy ship, so that it forms an angle with true north, a, tanA=X/Y=90T/ 120.

Y=( 120/90T)X

2. Hit the enemy ship, indicating that the coordinates of the missile and the enemy ship coincide. The enemy ship kept 120 due north, so when the missile Y= 120, they met. Y=( 120/90T)X= 120, X=90T, and the distance traveled by the missile =450*T= root number (y square +X square), that is, (450T) square =X square +Y square =(90T) square+.