shoot an object in a circle at runtime

I'd like to shoot an object in a circle that starts at the shooters location and then passes through where the mouse curser is and then returns to the shooter where it will be destroyed. I've tried using circular motion for active objects but don't seem to be able to find a way to control the radius during runtime.
Any help appreciated.
Steve

You'll need math knowledge.

Add an auxiliary [invisible] object to stand between the source(shooter) and destination(mouse). Use formulas to position it.

Then, using other formulas (use google or search the forums), make the object circle around the helper object with a radius equal to half the distance between mouse and shooter.

Thanks for the help. I figured out a way to do it, but it was a pain in the rump. I was hoping there was a simpler way to do it. The advanced direction object was very useful in that it saved me from typing in the formulas for the distance and the angle between the objects.
Steve