How Far Did Big Bertha's Shell Travel?

[steelblondie5]

Homework Statement

During World War 1, the Germans had a gun called Big Bertha that was used to shell Paris. The shell had an initial speed of 2.26 km/s at an initial inclination of 65.8 degrees to the horizontal. The acceleration of gravity is 9.8 m/s^2. How far away did the shell hit? Answer in units of km.
How long was it in the air? Answer in units of s.

Homework Equations

Vf= Vi + a (tf-ti)
y= yi + vit + 1/2 at^2.

The Attempt at a Solution

I did it several different ways and keep getting answers that are wrong. I got 4.10 s for time, then I got .420s and .840 s. I keep getting the wrong answer. Once I figure out how to do time, I'll be able to do the distance part. Keep in mind the a is in meters per second but kilometers is required in the answer.

 

[edziura]

Which of the two eqns did you use to find the time of flight t? What values did substitute?