To compensate for the natural visual distortion in which tall columns appear to bend inward, the greeks gave them a slight bulge, which is known

The answer to this question is entasis.

Entasis is a design principle in architecture where in a convex curve was applied to a surface which also serves a strength to the construction and it also gives an optical illusion to it. Egyptian pyramids use this design principle.

The answer is all of the above.

It depends on what type of third separates the three notes.for example: if you have two mayor thirds is an "aumented chord"if you have two minor thirds is an "diminued chord"if you have one mayor first and then one minor is a "mayor chord"and inverted is a "minor chord"