The +100 in the equations provides some extra clearance off screen, can be whatever you want.

If you created a 1000 objects and tested this it should draw a circle of them around the central point of your screen.

The equation uses Pythagoras equation (h? = x? + y?) to get the distance from top-left corner to bottom-right corner of the screen.

Then halves it (/2) to get central point to corner of the screen.

sin(angle) x hypot = opposite side (x) for X (s& = o/h)

cos(angle) x hypot = adjacent side (y) for Y (c& = a/h)

The X & Y values at this point would be offset around the 0,0 coordinate so now it's a case of adding half the width and height to offset around the center of the screen.

Of course, you might be able to store much of these calculations at app start to reduce computations.

I've put -200 in the formulas to get the spawn point on screen. Of course you can manipulate this to do any circular spawning around a point. This is just one application of it.