Field of view Projection

[EvanWeiss]

What I'm trying to is calculate the horizontal and vertical field of view that a rectangular object is occupying. This would be like calculating the field of view outside of a window that you are looking through. There is a website that can do this, but I'd like this in a formulaic form instead of being on a website. Thanks in advance. ...................................................................................................All I know so far is that you have to have the width and height of the object in question, As well as the distance to the object. This does not have to account for the fisheye effect which may distort the object. Also, sorry if this is posted in the wrong category, I barely understand the concept itself