Qualification > Math
IGCSE MATHS Doubts
Choc.Kits:
--- Quote from: A@di on May 17, 2010, 12:23:47 pm ---Radius = X
Height = y
Volume or W = 1/3 * x^2 * y * pi = (x^2ypi)/3
3 times --> Radius = 3x
Height = 3y
VOlume = 1/3 * pi * (3x)^2 * 3y = 9x^2y*pi
W = (x^2ypi)/3
Vol. = 9x^2y*pi
W * 27 = Vol.
27W
----------
cii) Radius = 2x
Height = y
Vol. = 1/3 * pi * (2x)^2 * y = (4x^2ypi)/3
W = (x^2ypi)/3
W * 4 = Vol.
Therefore, 4W
PS : Volume of a cone = 1/3*pi*r^2*h
--- End quote ---
Thanks a billion for that reply! I owe you ;)
Ghost Of Highbury:
Your welcome ..
Mr.DitD:
Hello everyone!!!
Can some1 please explain this question:
(c) A different cone, with radius x and height y, has a volume W.
Find, in terms of W, the volume of: (ii) a cone of radius 2x and height y.
http://www.freeexampapers.us/IGCSE/Maths/CIE/2009%20Nov/0580_w09_qp_4.pdf Q7 part (c)
???
Vin:
[
--- Quote from: Mr.DitD on May 17, 2010, 02:39:04 pm ---Hello everyone!!!
Can some1 please explain this question:
(c) A different cone, with radius x and height y, has a volume W.
--- End quote ---
--- Quote from: A@di on May 17, 2010, 12:23:47 pm ---Radius = X
Height = y
Volume or W = 1/3 * x^2 * y * pi = (x^2ypi)/3
3 times --> Radius = 3x
Height = 3y
VOlume = 1/3 * pi * (3x)^2 * 3y = 9x^2y*pi
W = (x^2ypi)/3
Vol. = 9x^2y*pi
W * 27 = Vol.
27W
----------
cii) Radius = 2x
Height = y
Vol. = 1/3 * pi * (2x)^2 * y = (4x^2ypi)/3
W = (x^2ypi)/3
W * 4 = Vol.
Therefore, 4W
PS : Volume of a cone = 1/3*pi*r^2*h
--- End quote ---
Mr.DitD:
--- Quote from: ~VIN1094~ on May 17, 2010, 02:40:50 pm ---[
--- End quote ---
I understand that Vol. = 1/3 * pi * (2x)^2 * y
But i dont know how it becomes: (4x^2ypi)/3
Can u please explain furthur if possible? Thanks a lot!!
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