Math Is Fun Forum

debjit625

Member

Registered: 2012-07-23

Posts: 101

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

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

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: Radius of a circular section of a sphere

hi debjit625

I get that too. 

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

debjit625

Member

Registered: 2012-07-23

Posts: 101

Re: Radius of a circular section of a sphere

Thanks Bob

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

Agnishom

Real Member

From: Riemann Sphere

Registered: 2011-01-29

Posts: 24,996

Website

Re: Radius of a circular section of a sphere

how do you do it?

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'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'
I'm not crazy, my mother had me tested.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: Radius of a circular section of a sphere

Give me a moment while I look up an url

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Agnishom

Real Member

From: Riemann Sphere

Registered: 2011-01-29

Posts: 24,996

Website

Re: Radius of a circular section of a sphere

Okay

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'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'
I'm not crazy, my mother had me tested.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

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

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

debjit625

Member

Registered: 2012-07-23

Posts: 101

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

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

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