Doubt about the procedure of parametrization












0












$begingroup$


I can't understand how parametrics equations are found. For example, I realize that the parametrization of the curve given by the intersection of the plane $ 2x+2y+z=2$ and $z=x^2+y^2$ is:




  • $x=-1+cos(t)$

  • $y=-1+sin(t)$

  • $z=6-2cos(t)-2sin(t)$

  • $0leqslant tleqslant2pi$


Or that the surface of $x^2+y^2=2$ delimited by $x^2+y^2+z^2=4$ is:




  • $x=sqrt2cos(u)$

  • $y=sqrt2sin(u)$

  • $z=v$


  • $0leqslant uleqslantpi/2$ and $0leqslant vleqslantsqrt2$


But what is the step by step to find those equations?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Are you sure you got these right? For the first problem $x^2+y^2=2-2x-2yimplies (x+1)^2+(y+1)^2=4$, which is inconsistent with your first two bullet points.
    $endgroup$
    – J.G.
    Dec 6 '18 at 6:36










  • $begingroup$
    Now I see it.I got them from a list and didn't check. What would be a correct parametrization then?
    $endgroup$
    – J.Doe
    Dec 6 '18 at 21:36










  • $begingroup$
    You need to double the trigonometric functions' coefficients.
    $endgroup$
    – J.G.
    Dec 6 '18 at 23:30
















0












$begingroup$


I can't understand how parametrics equations are found. For example, I realize that the parametrization of the curve given by the intersection of the plane $ 2x+2y+z=2$ and $z=x^2+y^2$ is:




  • $x=-1+cos(t)$

  • $y=-1+sin(t)$

  • $z=6-2cos(t)-2sin(t)$

  • $0leqslant tleqslant2pi$


Or that the surface of $x^2+y^2=2$ delimited by $x^2+y^2+z^2=4$ is:




  • $x=sqrt2cos(u)$

  • $y=sqrt2sin(u)$

  • $z=v$


  • $0leqslant uleqslantpi/2$ and $0leqslant vleqslantsqrt2$


But what is the step by step to find those equations?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Are you sure you got these right? For the first problem $x^2+y^2=2-2x-2yimplies (x+1)^2+(y+1)^2=4$, which is inconsistent with your first two bullet points.
    $endgroup$
    – J.G.
    Dec 6 '18 at 6:36










  • $begingroup$
    Now I see it.I got them from a list and didn't check. What would be a correct parametrization then?
    $endgroup$
    – J.Doe
    Dec 6 '18 at 21:36










  • $begingroup$
    You need to double the trigonometric functions' coefficients.
    $endgroup$
    – J.G.
    Dec 6 '18 at 23:30














0












0








0





$begingroup$


I can't understand how parametrics equations are found. For example, I realize that the parametrization of the curve given by the intersection of the plane $ 2x+2y+z=2$ and $z=x^2+y^2$ is:




  • $x=-1+cos(t)$

  • $y=-1+sin(t)$

  • $z=6-2cos(t)-2sin(t)$

  • $0leqslant tleqslant2pi$


Or that the surface of $x^2+y^2=2$ delimited by $x^2+y^2+z^2=4$ is:




  • $x=sqrt2cos(u)$

  • $y=sqrt2sin(u)$

  • $z=v$


  • $0leqslant uleqslantpi/2$ and $0leqslant vleqslantsqrt2$


But what is the step by step to find those equations?










share|cite|improve this question











$endgroup$




I can't understand how parametrics equations are found. For example, I realize that the parametrization of the curve given by the intersection of the plane $ 2x+2y+z=2$ and $z=x^2+y^2$ is:




  • $x=-1+cos(t)$

  • $y=-1+sin(t)$

  • $z=6-2cos(t)-2sin(t)$

  • $0leqslant tleqslant2pi$


Or that the surface of $x^2+y^2=2$ delimited by $x^2+y^2+z^2=4$ is:




  • $x=sqrt2cos(u)$

  • $y=sqrt2sin(u)$

  • $z=v$


  • $0leqslant uleqslantpi/2$ and $0leqslant vleqslantsqrt2$


But what is the step by step to find those equations?







parametrization






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 6 '18 at 6:29









Tianlalu

3,08621038




3,08621038










asked Dec 6 '18 at 6:09









J.DoeJ.Doe

1




1












  • $begingroup$
    Are you sure you got these right? For the first problem $x^2+y^2=2-2x-2yimplies (x+1)^2+(y+1)^2=4$, which is inconsistent with your first two bullet points.
    $endgroup$
    – J.G.
    Dec 6 '18 at 6:36










  • $begingroup$
    Now I see it.I got them from a list and didn't check. What would be a correct parametrization then?
    $endgroup$
    – J.Doe
    Dec 6 '18 at 21:36










  • $begingroup$
    You need to double the trigonometric functions' coefficients.
    $endgroup$
    – J.G.
    Dec 6 '18 at 23:30


















  • $begingroup$
    Are you sure you got these right? For the first problem $x^2+y^2=2-2x-2yimplies (x+1)^2+(y+1)^2=4$, which is inconsistent with your first two bullet points.
    $endgroup$
    – J.G.
    Dec 6 '18 at 6:36










  • $begingroup$
    Now I see it.I got them from a list and didn't check. What would be a correct parametrization then?
    $endgroup$
    – J.Doe
    Dec 6 '18 at 21:36










  • $begingroup$
    You need to double the trigonometric functions' coefficients.
    $endgroup$
    – J.G.
    Dec 6 '18 at 23:30
















$begingroup$
Are you sure you got these right? For the first problem $x^2+y^2=2-2x-2yimplies (x+1)^2+(y+1)^2=4$, which is inconsistent with your first two bullet points.
$endgroup$
– J.G.
Dec 6 '18 at 6:36




$begingroup$
Are you sure you got these right? For the first problem $x^2+y^2=2-2x-2yimplies (x+1)^2+(y+1)^2=4$, which is inconsistent with your first two bullet points.
$endgroup$
– J.G.
Dec 6 '18 at 6:36












$begingroup$
Now I see it.I got them from a list and didn't check. What would be a correct parametrization then?
$endgroup$
– J.Doe
Dec 6 '18 at 21:36




$begingroup$
Now I see it.I got them from a list and didn't check. What would be a correct parametrization then?
$endgroup$
– J.Doe
Dec 6 '18 at 21:36












$begingroup$
You need to double the trigonometric functions' coefficients.
$endgroup$
– J.G.
Dec 6 '18 at 23:30




$begingroup$
You need to double the trigonometric functions' coefficients.
$endgroup$
– J.G.
Dec 6 '18 at 23:30










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