What the hell are these calculations? Flat earthers are truly mistaken. These are incorrect calculations, and this is the basis for their theory. It's an ignorance of geometry, arithmetic, and Newtonian science.
How does a plane with a 157 ft.wing span enter the Pentagon and leave a 60 foot wide hole? There's no "angle" that could have managed that. Look at the aftermath- whatever it was didn't come in at an angle anyway.