4 unit Locus (1 Viewer)

[AFGHAN22]

Find the equation of the parabola focus (-3,-1) , directrix 3x-2y=5.
Btw the answer is 4x^2+108x+9y^2+6y+12xy=-105. I hope giving the answer does not stop people replying.

 

[shafqat]

Definition of parabola: distance from focus = distance from directrix
Use the distance formula for lhs, perp distance formula for rhs

 

[AFGHAN22]

thanx mate...any chance of u showing me. sorry i am only in year 11 and haven't come across questions of this nature.

 

[AFGHAN22]

btw shafqat...check ur email mate.

 

[justchillin]

Dude all you do is pick an arbitrary point P(x,y) then do what he said... use the distance formula from the focus and from a pt on the directrix...
If you wanted to be tricky, you could play with the defonition of a conic where the eccentricity, for a parabola, =1...

 

[tiggerfamilytre]

Quote: " ... any chance of u showing me"

Yes. I have plenty of time, so here is the working out. I suppose this is a fairly unusual year 11 question ... anyway it's just like shafqat and chillin said.

 

[AFGHAN22]

Thanks a lot for ur diagram an xplanation "tigerfamilytree". U r a champion. Thanks once again.