Need to get an equation for when it is tangent

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Discussion Overview

The discussion revolves around finding the equation of a sphere that is tangent to the yz-plane and the line y=7, given a center point of (3,-1,-2). Participants are exploring the mathematical relationships and conditions necessary for tangency.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant seeks assistance in determining the equation of a sphere tangent to the yz-plane and y=7, expressing confusion about which coordinates to use.
  • Another participant asks for the general formula for a sphere, indicating a need for foundational understanding.
  • A participant provides a formula for the sphere but incorrectly uses the variable x in the equation, which is later corrected to include the correct variables for y and z.
  • There is a discussion about what variable must be zero for the sphere to be tangent to the yz-plane, prompting further clarification on the equation of the yz-plane.
  • Another participant emphasizes the need to identify a single point on the yz-plane and questions how to find the distance between that point and the center of the sphere.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the correct approach to find the tangency conditions, and multiple viewpoints and methods are presented without resolution.

Contextual Notes

Participants express uncertainty regarding the choice of coordinates for tangency and the application of the distance formula, indicating potential limitations in their understanding of the geometric relationships involved.

Who May Find This Useful

This discussion may be useful for students studying geometry, particularly those working on problems involving spheres and tangency conditions in three-dimensional space.

bharp24
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I need someone to help me! i have been given a center point of (3,-1,-2) of a sphere and i need to get an equation for when it is tangent to the a) the yz plane b) y=7. i know i need to use the distance formuala to attain the radius, but i am majorly confusing myself in what coordinate to pick. Do i just use (0,0,0) as tangent point to the plane for a)?? please help!
 
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What is the general formula for a sphere?
 
what i have so far is (x-3)^2 + (x+1)^2 + (x+2)^2= r^2. i just need to find the radius of this equation, so that the sphere will be tangent to the yz plane. once i know the coordinates to use for the tangent point, i can use the distance formula to give me the radius.
 
It would actually be ...

[tex](x-3)^2+(y+1)^2+(z+2)^2=r^2[/tex]

If you want it tangent to the yz-plane, what variable must be 0?
 
that is what i meant..sorry. i still need to know what the equation would be though to figure out when it is tangent to the yz plane.
 
So you want a single point to be on the yz plane. What is the equation of the yz plane?
At what point of the sphere is that equation true? What is the distance between that point and the center of the sphere?
 

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