Math Talk Math Talk    FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Yahoo Answers question          Math Talk Forum Index -> Math Talk View previous topic :: View next topic   Author Message Jeremy Watts Guest Posted: Fri Jun 27, 2008 5:41 pm    Post subject: Yahoo Answers question I saw this question posed on Yahoo Answers, and straight off I admit I cant get it to work out... Anyone know? "A point P moves in such a way that the product of its distances from the lines 4x+3y=0 and 4x-3y=0 is 4. Find the equation of the locus of P" Back to top   Ads Advertising Sponsor G.E. Ivey Guest Posted: Fri Jun 27, 2008 5:41 pm    Post subject: Re: Yahoo Answers question Quote: I saw this question posed on Yahoo Answers, and straight off I admit I cant get it to work out... Anyone know? "A point P moves in such a way that the product of its distances from the lines 4x+3y=0 and 4x-3y=0 is 4. Find the equation of the locus of P" Given any point P= (x,y), its distance from the line Ax+ By= 0 is given by |Ax+ By|/sqrt(A^2+ B^2}. Your first line has A= 4, B= 3 so the distance from (x,y) to it is |4x+ 3y|/5. Your second line has A= 4, B=-3 so the distance from (x,y) to it is |4x- 3y|/5. Saying "the product of the distances is 4" means that (|4x-3y|/5)(|4x+3y|/5)= 4 or |16x^2- 9y^2|= 20. Back to top   Ads Advertising Sponsor Jeremy Watts Guest Posted: Fri Jun 27, 2008 7:02 pm    Post subject: Re: Yahoo Answers question "G.E. Ivey" <george.ivey@gallaudet.edu> wrote in message news:2131894.1214573786936.JavaMail.jakarta@nitrogen.mathforum.org... Quote: I saw this question posed on Yahoo Answers, and straight off I admit I cant get it to work out... Anyone know? "A point P moves in such a way that the product of its distances from the lines 4x+3y=0 and 4x-3y=0 is 4. Find the equation of the locus of P" Given any point P= (x,y), its distance from the line Ax+ By= 0 is given by |Ax+ By|/sqrt(A^2+ B^2}. Your first line has A= 4, B= 3 so the distance from (x,y) to it is |4x+ 3y|/5. Your second line has A= 4, B=-3 so the distance from (x,y) to it is |4x- 3y|/5. Saying "the product of the distances is 4" means that (|4x-3y|/5)(|4x+3y|/5)= 4 or |16x^2- 9y^2|= 20. of course yes... i was messing around with scalar products.. thanks Back to top   Ads Advertising Sponsor Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         Math Talk Forum Index -> Math Talk All times are GMT Page 1 of 1   Jump to: Select a forum Math Talk----------------Math Talk  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Australian Debt Consolidation Experts medical insurance Wedding Invitation Escort, massaggiatrici e accompagnatrici a Modena, Bologna, Parma, Brescia, Vicenza ... Swingers in Germany Insurance Talk cheap mortgages Make Your Own Website Free calls to Pakistan Long island Cleaning service toxic mold UK Swingers Genuine Contacts Site Adult Dating office supplies Wines Vacuum Bags 199 Attacks blocked Powered by phpBB © 2001, 2005 phpBB Group