The PERIMETER of the equator cycle is about 40,000Km. The Greenwich cycle is a bit shorter as the earth is a bit an ellipsoid. About 37,000Km by Google Maps. The distance on the envelope between ANY antipodes (=opposite points on the axis, I won't use "diameter" to avoid confusion) is HALF the perimeter (If you walk the whole perimeter long, you'd get to the same point, of course). The distance through Earth is
D=P/Pi=37,000Km/Pi=about11777Km
The world is round not flat cause first look image your viewing a picture of earth actually the earth is not really round its a shape called an ellipsoid which is kind of squatters and fat plus the world is round cause of the force of gravity
I am very confused? Would you mind telling me what it means so I can help
<span>The Ring of Fire is a major area in the basin of the Pacific Ocean where a large number of earthquakes and volcanic eruptions occur. In a 40,000 km horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and/or plate movements. It has 452 volcanoes. The Ring of Fire is sometimes called the circum-Pacific belt.
source: wikapedia</span>
I think the answer is C but unfortunately I am not 100% sure.