A simple search on the internet is not enough to answer this question. A knowledge of geometry has to be present in order to answer this question satisfyingly.
sector
no. it is not square shaped. it just means it is in the center of a big city or near the center.
It is shaped like a Sphere
Intensity of rings formed depends on thickness of air column between the lens and glass plate.And the locus of points having same thickness of air column above it is a circle with its center as the point of contact between the glass plate and lens.
The channel is U-shaped cross-section, while the crossbeam is can be divided into H-plate, I-beam, etc. Both of them have different uses.
The Fertile Crescent
It looks like you meant width or thickness. This is the formula to calculate volume or capacity of a rectangular prism (a box).
eclipse
They need not be. Many electromagnets are circular disks or toroidal (donut shaped). Bar magnets, not surprisingly, are bar shaped - often with a rectangular cross section.
Finding the center of gravity of an irregularly shaped object can be done using the plumb line method.
No - the iPod touch is significantly thinner than the iPhone and is also shaped differently.
they are objects shaped in straight sides, circular ends of equal size, and a constant circular cross section.