Curved Shape Polylines Not Closing


I am attempting to make the below shape into a roof of a building, but every time I try to extrude it and cap it, it says that it cannot cap it because there are open curves. When I use the CloseCrv command, it gives me the result on the right. If you have any advice for dealing with a shape such as this, I would really appreciate it.

Hello- Join the curves, then extrude.


Thank you so much!