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fab13
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Mod note: Moved from a technical forum section, so missing the homework template.
@fab13 -- please post homework problems in the appropriate section under Homework & Coursework.
I have the following exercise to solve : I have to find all the points on the surface ##x^2+y^2+z^2=36## (so a sphere of radius = 6) where tangent planes are parallel to plane ##3x+4y+5z=0##
For the moment, I can get this reasoning :
if ##M_{0}=(x_0,y_0,z_0)## is a point that staisfies the wanted property above and ##(x,y,z)## a point of its tangent plane, I have (with ##C## the center of the sphere) :
[tex]\vec{CM_{0}}\cdot \vec{MM_{0}}=0[/tex]
So with the sphere of equation : ##(x-a)^2+(y-b)^2+(z-c)^2=R^2##, I can deduce :
##(x_0-a)(x-x_0)+(y_0-b)(y-y_0)+(z_0-c)(z-z_0)=0## and especially :
##(x_0-a)(x-a)+(y_0-b)(y-b)+(z_0-c)(z-c)-R^2=0##
In my case, ##R^2=36## and ##a=b=c=0##, so I have :
##x_0 x +y_0 y +z z_0 -36=0##
From this point, how can I deduce ##(x_0,y_0,z_0)## ( I recall, the tangent plane at this point has to be parallel to plane ##3x+4y+5z=0##) ?
Thanks for your help
@fab13 -- please post homework problems in the appropriate section under Homework & Coursework.
I have the following exercise to solve : I have to find all the points on the surface ##x^2+y^2+z^2=36## (so a sphere of radius = 6) where tangent planes are parallel to plane ##3x+4y+5z=0##
For the moment, I can get this reasoning :
if ##M_{0}=(x_0,y_0,z_0)## is a point that staisfies the wanted property above and ##(x,y,z)## a point of its tangent plane, I have (with ##C## the center of the sphere) :
[tex]\vec{CM_{0}}\cdot \vec{MM_{0}}=0[/tex]
So with the sphere of equation : ##(x-a)^2+(y-b)^2+(z-c)^2=R^2##, I can deduce :
##(x_0-a)(x-x_0)+(y_0-b)(y-y_0)+(z_0-c)(z-z_0)=0## and especially :
##(x_0-a)(x-a)+(y_0-b)(y-b)+(z_0-c)(z-c)-R^2=0##
In my case, ##R^2=36## and ##a=b=c=0##, so I have :
##x_0 x +y_0 y +z z_0 -36=0##
From this point, how can I deduce ##(x_0,y_0,z_0)## ( I recall, the tangent plane at this point has to be parallel to plane ##3x+4y+5z=0##) ?
Thanks for your help
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