Analysis: The idea of solving the problem is as follows: first, find out the diameters of two circles (the circle formed by the equator and the circle formed by the elongation of the equator), and then find out half of the difference between the diameters of the two circles, that is, how many kilometers is the distance from the "belt" to the ground. Assuming that the diameter of the circle formed by the equator is D, and the diameter of the circle formed after the equatorial "belt" is lengthened by 10 km is D, then D = 40000/π.

D = (40000+10)/π = 400 10/ π (d-d)/2 =10/2π ≈1.5 km, so the distance between the belt and the ground is/kloc-0. The puppy can pass completely.

I hope I can help you and adopt it.