Here's the math...
Consider that 94-deg is a cone with the camera at the apex. To compute the base you need to divide the cone in half to result in a right triangle so to be able to apply the trigonometric function of "B(base)/H=tan-1 ("H" being the height, or altitude). But since we're solving for "B" we need to use the tangent of 47-deg (half of 94-deg), which is 1.0724. At a height of 500m x 1.074 (the tangent) B=536.18m. Remember that this half the cone so we need to double this to get back to the 94-deg FOV, which rounded is 1072m. This is the FOV at 500m per your question. I'm OK with geometery, but what you will actually see in your final image will be determined by your format and that is for someone else to compute.