What is the area formula of traditional shapes?

First, find the circumference of a circle with infinite approximation.

π=n*sin(45 /n)*4？ (n & gt700000)

L=2πr

r/△x=n

Then △ x * * 2π 0+△ x * 2π△ x+△ x * 2π 2 △ x+... △ x * 2π△ x (n-1) = 2π△ x 2 * (n (n-1)/2 = lim？ N→ infinity? Get π r 2

See if it's okay?

There is a more complicated one? Don't want to fight? Go to bed? We'll talk tomorrow.