Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

You are not logged in.

## #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

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

Thanks

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

Offline

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

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,067

### Re: Radius of a circular section of a sphere

hi debjit625

I get that too.

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

Offline

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

Offline

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

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 21,757
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'
'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

Offline

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

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,067

### 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

Offline

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

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 21,757
Website

### 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'
'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

Offline

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

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,067

### 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.

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

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

Offline

## #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

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

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

Offline