Firstly, it has to be said that it is not NASA that started to give evidence for the flat earth. An Ancient Greek philosopher, Eratosthenes, calculated that the earth is actually a sphere and found its size using shadows and simple mathematics. This can be repeated by anyone today. So we know from the observational evidence that the earth is round. Unless of course, the flat earthers want us to think that the conspiracy to make the earth look flat went on for about 2000 years.
That is it for my first argument. I'll give the rest of my argument after someone accepts the challenge.
Well i know that earth is sphere. And as far as i know you may be correct but not only that man, but ferdinand magallen also proved that earth is round. He took a voyage and moved straight and after some days he reached the same place from where he started. That proved that earth is round.