Mmmmm Pie. I like Pie, especially when I am looking for badguys in structures or urban terrain.
“Slicing the Pie” or “Pieing” a corner is the term used for a technique used to traverse a corner while clearing a structure or while maneuvering around structures/objects out of doors.
In general, there are but a small handful of methods for dealing with corners, rooms, stairwells etc. You can “button hook” directly into the area and deal with whats there. This is typically a “dynamic” tactic where speed of entry and aggressive action is required. Or you can “Slice the Pie” to negotiate the turn, which is a systematic clearing of the area in “slices”.
The way you accomplish this is by approaching the corner fairly close to the wall with your “pivot point” being the apex of the corner. You then begin a series of small 90 degree side-steps (relative to your line of sight) away from the wall, in a semi-circular manner. After every step you pause and scan each “slice of the pie” from the floor at the corner to the ceiling.
There you go…easy as pie.