A cone-shaped pile of fertilizer with a circumference of 62.8 meters and 5 meters at the bottom. If 20 cubic meters of fertilizer is applied to each hectare of land, how many hectares of fertilizer can be applied

A cone-shaped pile of fertilizer with a circumference of 62.8 meters and 5 meters at the bottom. If 20 cubic meters of fertilizer is applied to each hectare of land, how many hectares of fertilizer can be applied

Ground radius 62.8 △ 2x3.14 = 10m
Volume 1 / 3 x 10 x 3.14 x 1.5 = 157 M3
157 △ 20 = 7.85 ha
A: the fertilizer can be applied to 7.85 hectares

A cone fertilizer pile has a perimeter of 12.56 meters and 8 meters at the bottom. If 20 cubic meters of fertilizer is applied to each hectare of land, how many hectares of land can this pile of fertilizer be applied to?
I'd better understand the formula and the reason

The first step is to calculate the volume of the fertilizer pile. According to the 2 Pai x radius of the perimeter, we can get: radius = 12.56 △ 2 △ 3.14 = 2, area = radius × radius × Pai = 4 × 3.14 = 12.56 square meters, volume = bottom area × height = 12.56 × 1.8 = 22.608 cubic meters, every 20 cubic meters of fertilizer 1 hectare, then we can fertilize 22.608 △ 20 = 1.1

The perimeter of the bottom surface of a cone-shaped fertilizer pile is 12.56 meters and 8 meters. If there is no 20 cubic decimeters of fertilizer per hectare of land, how many hectares of land can these fertilizers supply

The volume of this pile of fertilizer = (1 / 3) π [12.56 / 2 π] & # 178; × 1.8
=536 (m-179;) (take π = 3.14)
=7536 (decimeter and 179;)
If 20 cubic decimeters of fertilizer is applied per hectare, the fertilizable area of this pile of fertilizer is as follows:
7536 △ 20 = 376.8 (HA)