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![[Post New]](/templates/default/images/icon_minipost_new.gif) 6 Sep 2008 19:58:25 IST
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If two tangents to the parabola y2=4ax makes angle A& B with the X axis and tan2A +tan2B=c.Find the locus of the point of intersection of the tangents.
Please show how 2 solve....rates assured
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![[Post New]](/templates/default/images/icon_minipost_new.gif) 7 Sep 2008 17:09:28 IST
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i think this is simple....consider any 2 points (at12,2at1) and (at22,2at2) let tangents be drawn from these points....then the slope of tangent from point1 is 1/t1=tanA and from pt2 is 1/t2=tanB let (x,y) be the point of intersection of the tangents....then x=at1t2 and y=a(t1+t2) i am not very sure of this formula... but i think it is correct....now all u have to do is eliminate t1 and t2 from the given relation we have (t12+t22)/t12.t22 =c =>((t1+t2)2-2t1.t2)/(t1.t2)2=c => (y/a)2-2x/a=c(x/a)2 so the ans is cx2+2ax=y2.....
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