Please look at question carefully. Max Range is easy. But, there is also a second question. How close to the shore should the boat get, so that it is protected by the peak. What formula can you use to figure that out.

An enemy ship is on the east side of a mountainous island. The enemy ship can maneuver to within 2500 meters of the 1800 meter high mountain peak and can shoot projectiles with an initial speed of 250m/sec. If western shoreline is horizontally 300 meters from the peak, what are the distances from the western shore at which a ship can be safe from the bombardment of the enemy ship?