(1) a wire 32 cm long, is bent into the shape of a qusdrant. Find the area enclosed by wire.
(2) A water pipe of internal diameter 2.6cm delivers water at a rate of 0.8m/s.How much water comes outper second.
有兩條英文數學題唔識(圓周) (要有步驟)
2009-09-01 11:02 pm
回答 (1)
2009-09-01 11:28 pm
✔ 最佳答案
Q1.Let radius of quadrant = r
Perimeter of quadrant = r + r + 2pr(90/360) = 2r + pr/2 (p = pi)
so 2r + pr/2 = 32
4r + pr = 64
r(4 + p) = 64
r = 64/(4 + p).
so area enclosed = pr^2/4 = (p/4)[64/(4 + p)]^2 = 1024p/(4 + p)^2.
Q2.
In 1 sec. length of water running out = 0.8m = 80 cm.
so volume of water running out = p(2.6/2)^2(80)
= p(1.3)^2(80) = 135.2p cm^3.
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