中三程度:兩條數學題,求解答

2011-05-22 7:36 pm
1. Show that the volume V of a sphere with diameter d and surface area A is given by V= 1/6 Ad.

2. Air is leaking out from a spherical balloon. Find the percentage decrease in its volume when its surface area has decreased by 36%.

回答 (1)

2011-05-22 7:53 pm
✔ 最佳答案
1 V = (4/3)πr^3 where A = 4πr^2

So, V = (4πr^2)(1/3)(r) = A(1/3)(d/2) = (1/6)Ad

2 Surface new : Surface original = 0.64 : 1

So, Volume new : Volume original = (√0.64)^3 : 1 = 0.512 : 1

The percentage decrease is (1 - 51.2%) = 48.8%


收錄日期: 2021-04-15 15:27:07
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110522000051KK00322

檢視 Wayback Machine 備份