obwód koła 英語で:

Is it possible to determine the diameter from the circumference?

the island is 100 km in circumference

The circumference of the circle measures around 31 centimetres.

The main road leads around the circumference of the island.

God is an infinite sphere whose center is everywhere and circumference is nowhere.

The world can no more have two summits than a circumference can have two centres.

How do you derive the length of the circumference? I've forgotten.