3D kinematics problem with horizontal range

[togame]

Homework Statement

I know pictures aren't the best, but here it is.

Homework Equations

The Attempt at a Solution

This is my work for this problem. Disregard the drawing as it isn't right.

I'm not sure if I'm misinterpreting the horizontal range part or what. I feel pretty confident about my work but webassign says it's wrong and I don't really see why.

Link to original if it's not big enough

 

[SteamKing]

The horizontal range of the plane means its distance from the radar site without including the plane's altitude.
You are treating the horizontal range as the distance to the east, which is incorrect.

 

[togame]

The horizontal range of the plane means its distance from the radar site without including the plane's altitude.
You are treating the horizontal range as the distance to the east, which is incorrect.

Ahhh. You were absolutely spot on. I was unaware that they were using horizontal in the sense of x and y. Thank you very much.