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#1 2014-01-20 19:33:56

debjit625
Member
Registered: 2012-07-23
Posts: 91

Radius of a circular section of a sphere

Find the radius of the circular section of sphere

by the plane

My answer came out to

Did I did it correctly,I am bit confused over the question.

Thanks


Debjit Roy
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The essence of mathematics lies in its freedom - Georg Cantor

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#2 2014-01-20 21:42:26

bob bundy
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Registered: 2010-06-20
Posts: 6,532

Re: Radius of a circular section of a sphere

hi debjit625

I get that too.  smile

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#3 2014-01-20 23:37:49

debjit625
Member
Registered: 2012-07-23
Posts: 91

Re: Radius of a circular section of a sphere

Thanks Bob


Debjit Roy
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The essence of mathematics lies in its freedom - Georg Cantor

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#4 2014-01-21 04:24:18

Agnishom
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From: The Complex Plane
Registered: 2011-01-29
Posts: 18,885
Website

Re: Radius of a circular section of a sphere

how do you do it?


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
'You have made another human being happy. There is no greater accomplishment.' -bobbym

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#5 2014-01-21 04:54:16

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,532

Re: Radius of a circular section of a sphere

Give me a moment while I look up an url

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#6 2014-01-21 04:56:30

Agnishom
Real Member
From: The Complex Plane
Registered: 2011-01-29
Posts: 18,885
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Re: Radius of a circular section of a sphere

Okay


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
'You have made another human being happy. There is no greater accomplishment.' -bobbym

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#7 2014-01-21 05:00:48

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,532

Re: Radius of a circular section of a sphere

OK.  Got it.

You could treat the two equations as simultaneous and find the equation of their intersection.  Buit this is hard work.  So here's a quicker method.

http://www.enm.bris.ac.uk/admin/courses … ov2009.pdf

Section called Point and a Plane.  3.37

n is the normal to the plane ie n = (3,2,-1) and take a as a = (0,0,0)

d = 5root14

once you have p you can use pythag on the radius of the sphere as the hypotenuse and find r, the radius of the circle.

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#8 2014-01-23 03:50:03

debjit625
Member
Registered: 2012-07-23
Posts: 91

Re: Radius of a circular section of a sphere

Well I did it like this
By equation of the sphere its already given that the sphere is at origin (0,0,0).
Now from there we get radius of the sphere is



Now we have to find the distance 'd' of the plane
from origin
and that will be


Now use Pythagoras theorem to find the radius of the section by the plane

Good Luck smile

Last edited by debjit625 (2014-01-23 03:56:16)


Debjit Roy
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The essence of mathematics lies in its freedom - Georg Cantor

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