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Jonask
 2 years ago
prove that the directrix of an ellipse is \[x=\frac{a^2}{c}\]
Jonask
 2 years ago
prove that the directrix of an ellipse is \[x=\frac{a^2}{c}\]

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Jonask
 2 years ago
Best ResponseYou've already chosen the best response.0this ellipse is the general ellipse with \[\frac{ x^2 }{ a^2}+\frac{ y^2 }{ b^2 }=1,a>b\]

Jonask
 2 years ago
Best ResponseYou've already chosen the best response.0i have the proof but i dont understand the ratio set up here can i post the link

Jonask
 2 years ago
Best ResponseYou've already chosen the best response.0\[r=\frac{ ac }{ da }=\frac{ a }{ d }\]

Jonask
 2 years ago
Best ResponseYou've already chosen the best response.0\[a^2=b^2+c^2 i dont get this ratio .why it holds

experimentX
 2 years ago
Best ResponseYou've already chosen the best response.1??dw:1364055606757:dwdw:1364055629069:dw

experimentX
 2 years ago
Best ResponseYou've already chosen the best response.1i haven't done conics for quite while, but this shouldn't be difficult.dw:1364055735803:dw

Jonask
 2 years ago
Best ResponseYou've already chosen the best response.0i mean http://mathworld.wolfram.com/images/equations/Ellipse/NumberedEquation12.gif

Jonask
 2 years ago
Best ResponseYou've already chosen the best response.0its defined in the 1st link

experimentX
 2 years ago
Best ResponseYou've already chosen the best response.1can't find it ... equation no?

experimentX
 2 years ago
Best ResponseYou've already chosen the best response.1what is this 'c' again?

experimentX
 2 years ago
Best ResponseYou've already chosen the best response.1this 'c' looks like foci.

experimentX
 2 years ago
Best ResponseYou've already chosen the best response.1this is pretty ovbioius ... this ratio must be constant
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