Trajectory Problem: Shooting a cannon

[nadong2dong]

Homework Statement

A pirate ship is on a waterfall above a fort. The height of the waterfall is 200m above the fort. The pirate captain fires a cannon with an initial velocity 40m/s at angle of 40 degrees. If the cannonball makes a direct hit on the fort, how far away(horizontally) was the pirate ship when it fired.

Homework Equations

First find x and y comp.
40cos45=28.28m/s
40sin45=28.28m/s

final velocity^2 = initial velocity^2 +2ad
Final velocity^2= (40^2) + 2(-9.8)(-200)
final velocity= 74.3m/s

final velocity= initial velocity + at
74.3m/s= 40m/s+(-9.8)t
t= 3.5s

Velocity(x-direction) x t= horizontal distance
28.23 x 3.5s = 98.98m

The Attempt at a Solution

98.98m

 

[nadong2dong]

I want to know if i correctly solved the problem.