The equator.
The equator and all lines of longitude are called great circles because the represent the circumference of the earth. The other latitude lines along the globe are smaller then the actually circumference.
circumference = 2*pi*radius or pi*diameter
An arc
It is an arc
The circumference of a circle = pi*diametre = 2pi*radius
The circumference of the planets vary. Mercury has a circumference of 9,522 miles. Venus has a circumference of 23,617 miles. Earth has a circumference of 24,889 miles. Mars has a circumference of 13,256 miles.
Then they are similar.
The ratio of the circumference of a circle to its diameter is Pi. (3.14159)
Pi times the diameter of a circle gives its circumference.
The polar circumference of the Earth is any great circle that includes both poles. It is shorter than the equatorial circumference because the Earth's spin makes it bulge at the equator, while it is flattened at the poles. The polar circumference at MSL would be 40,008 km, compared to the equatorial circumference of 40,075 km.The term "polar circumference" can also refer to the Arctic and Antarctic circles, which are roughly 66.56 degrees N and S latitude.
The equator, around Earth's total circumference as a sphere.
Okay, for starters, circumference is used only for circles and spheres. the UK is neither so therefore it has no circumference.