Question

the diameter of the earth at the equator is about 8,000 mi. Based on this figure ,how far is it exactly around the earth

Answer 1

C = 2 π r
C = 8,000 π or 25,133 miles

Answer 2

basically, we want to find the circumfernece of the earth
C=pid
d=diameter
pi=pi (aprox pi=3.1419256)
C=3.14159256*8000
C=25132.74048 feet