How could the Earth possibly be flat? How? Just How?

We know it is not.
However, over two thousand years ago, even when they already knew the Earth to be "round", some Greek philosophers and geometers imagined the possibility that the Earth was a cylinder: two ends that are flat and round, and the "round side" being geometrically "flat" (translation in geometry = angles in a triangle add up to 180 degrees).

Some thought we lived on one of the flat ends, with the other end facing the "central fire" which everything orbits, including the Sun (perfect mirror) and the Moon (imperfect mirror). This was the only position that explained the shape of eclipses.
However, another group (of the "cylinder-Earthers") thought that we lived on the round side, which was the only way to explain how the declination of the zenith changed when travellers moved north-south.

The two concepts (flat end versus round side) were mutually exclusive (they could not be both right); unfortunately, they were also complementary (both conditions must be met).

Even back then, the majority thought the Earth was a sphere.

The main difference between a flat surface (plane trigonometry) and a positively curved surface (spherical trigonometry) is in the sum of angles in a triangle.
On a plane, this sum will always be 180 degrees, regardless of the size of the triangle. On a sphere, the sum will be more than 180, with the spherical excess increasing as the size of the triangle increases. Back then, instruments were not precise enough to measure the difference.

Nowadays, we can. And there are other ways to show that plane trigonometry fails as triangles get bigger on Earth.

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To answer your question: How COULD it be flat? by being a cylinder.

It couldn't. It's a sign of internet psychopathology.

Everyone knows it's not flat - there's just a few that like to stir up arguments... I smile & walk away - the best response to idiocy is silence.

Flat is in the eye of the beholder ... and the rest of us know better.

How could people believe in gods? Our to ignore facts and accept only what they want to believe is what makes us human.

There is no way Earth can be Flat. None at all.

Consriracy theories from people who dont understand gravity beyond "stuff fall down"

Most people don't need to know much about science in their daily lives. Some people take that a bit further and choose to believe whatever fantasy pops into their head.

It can't be, obviously.

What are you asking?

It's not possible, and isn't flat.

If it were flat , then it must have its thickness .

Some People are just plain Dumb as a Brick
But Liberals hold us to respect them

Its isn't flat, that's how.

um, it's not. have you not seen the space photos?

It's not. It's just flat from an Earth bound perspective

That was one of the question posed by the natives of the large plains in the west of USA. how come mother earth is so flat.
Flatness is measured as a function of Curvature. Its calculated using simple geometry

Look to the pizza. The world in microcosm.