conics prob. (1 Viewer)

[conics2008]

hi.. im having trouble proving this identity..

if the tangent to the ellipse at P and the tangent to the circle at R are CONCURRENT with the right hand directrix of the ellipse, show that sec @ = 2/e where e is the eccentricity of the ellipse

ellipse = x^2/a^2 + y^2/b^2 =1
circle = x^2+y^2=a^2

wtf is CONCURRENT and wtf do we sub in.. i tried subbin in x=a/e but no hope into the equation of the tangent both in ellipse and circle..

btw P is ( acos@,bsin@) R is (acos%,bsin%)

thank you... im just getting confused.

 

[lolokay]

concurrent means the lines pass through a single point - one line passes through the point of intersection of the other 2

 

[vds700]

hi.. im having trouble proving this identity..

if the tangent to the ellipse at P and the tangent to the circle at R are CONCURRENT with the right hand directrix of the ellipse, show that sec @ = 2/e where e is the eccentricity of the ellipse

ellipse = x^2/a^2 + y^2/b^2 =1
circle = x^2+y^2=a^2

wtf is CONCURRENT and wtf do we sub in.. i tried subbin in x=a/e but no hope into the equation of the tangent both in ellipse and circle..

btw P is ( acos@,bsin@) R is (acos%,bsin%)

thank you... im just getting confused.

I believe there is a mistake in this question- I couldn't do it, so I asked my tutor, and he couldn't prove it, then he tested it to see if it was true and found that it wasn't. Maybe they made a typo when typing up these questions or something.

 

[vds700]

I found the original paper, and there seems to be no difference in the question.

 

[Pwnage101]

btw, that is NOT THE ACTUAL CSSA TRIAL, that is the trial typed up by some dude into that format, and teh guy must ahve made some mistakes, ive found several mistakes in tehc atholic trials found in that format - the person who types it to that format DOES MAKE ERRORS, and this must be one of them

 

[conics2008]

thanks guys. stupid cssa.. but thats not the paper i had.. its like topic by topic papers ive got from past hsc/cssa papers all in topic.

stuff these papers.. they are insane long... how much are they expecting off us ?>???

 

[vds700]

thanks guys. stupid cssa.. but thats not the paper i had.. its like topic by topic papers ive got from past hsc/cssa papers all in topic.

stuff these papers.. they are insane long... how much are they expecting off us ?>???

I reckon those topic by topiuc questions are good (despite some mistakes). They have just sorted past cssa questions by topic and given the answers underneath, which i think is great. The paper I attached above is the original paper that the question conics is asking about came from (1996 cssa).

 

[conics2008]

I reckon those topic by topiuc questions are good (despite some mistakes). They have just sorted past cssa questions by topic and given the answers underneath, which i think is great. The paper I attached above is the original paper that the question conics is asking about came from (1996 cssa).

hey yeh your right. like it has a short and simple answer. Its great it also encourage students to look for other way to solve the question. having the soultion at the back makes them lazy and just want to look at the answer. ive completed complex/poly/graphs and right now on conics soon ill do volumes and mechanic..

hey may i ask where do u find these papers from.. ??????

 

[moll.]

i tried the problem and got sec@ = 1/e
i can't be bothered explaining what i did, but either the paper's wrong or i forgot to carry the one somewhere.
i'm leaning toward the former.
it makes me look better.

 

[conics2008]

i tried the problem and got sec@ = 1/e
i can't be bothered explaining what i did, but either the paper's wrong or i forgot to carry the one somewhere.
i'm leaning toward the former.
it makes me look better.

hmmmmm do u like cake ???

 

[moll.]

hmmmmm do u like cake ???

I'm really more of a chips person.

 

[vds700]

hey may i ask where do u find these papers from.. ??????

http://au.geocities.com/ext2papers/

 

[tommykins]

回复: Re: conics prob.

I also got 1/e.

 

[conics2008]

Re: 回复: Re: conics prob.

Hey guys. Here is another conics question


x^2/9 − y^2/16 = 1.

Prove that the tangent intercepted between the asymptotes subtends a constant angle
at a focus.

 

[conics2008]

Re: 回复: Re: conics prob.

Hey guys. Here is another conics question


x^2/9 − y^2/16 = 1.

Prove that the tangent intercepted between the asymptotes subtends a constant angle
at a focus.

help please ?