Closely guarded? No. Just throw out your arms.

[rainmaker]

Originally posted by Cager ref 1989
Most HS players are, on avg., 6 ft tall.
If a HS player is standing at a distance that once lying flat on floor would be touching their opponent, BEGIN THE COUNT, they are close enough. What are we waiting on?

This is how I judge it, although I adjust for whether the player is taller or shorter than 6 feet. I've also heard that it can be guestimated by whether both sets of hands reaching straight out to each other would touch. I simply can't visualize the radius of the free throw circle.