There's no math to this,
So I don't see why angle is in the question anyways...
The sun provides energy for animals and plants. A cave is a type of ecosystem that almost never sees the sunlight, and a forest is a type of ecosystem that sees the sunlight regularly. The difference between these two is- the caves have animals that have adapted to their environment, I think there's a species called ghost crabs that are blind and are white. This is because sunlight provides the vitamins to pigment skin. I could go on and on