Advanced mathematics, the fourth question, how to find the area by integral? I don't understand this answer.
Gosh, didn't you already choose A? Lemniscate's integral area formula should be remembered, just like 1+ 1=2. This is a theorem formula, which must be remembered. If you need to know why that formula must be like that, it is meaningless. Just like you learn 1+ 1=2, it doesn't make much sense. thank you