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 2 years ago
11.2 the Parabola. Its says Conic sections:
suppose PQ is a focal chord of the parabola y=x^2 and that the coordinates of P are (2,4)
a)find coordinate of Q
b)find coordinates of M, the midpoint of PQ.
c) A perpendicular is drawn from M to the y axis, meeting the y axis at S. Also, a line perpendicular to the focal chord is drawn through M, meeting the yaxis and T.
Find ST, and verify its equal to onehalf the focal width of the parabola.
 2 years ago
11.2 the Parabola. Its says Conic sections: suppose PQ is a focal chord of the parabola y=x^2 and that the coordinates of P are (2,4) a)find coordinate of Q b)find coordinates of M, the midpoint of PQ. c) A perpendicular is drawn from M to the y axis, meeting the y axis at S. Also, a line perpendicular to the focal chord is drawn through M, meeting the yaxis and T. Find ST, and verify its equal to onehalf the focal width of the parabola.

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lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0whats a focal chord? I was givin this homework problem and instructor confused me on all the different positions

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0Any chord to y2 = 4ax which passes through the focus is called a focal chord of the parabola y2 = 4ax.

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0@lilsis76 tell me the focus of ur parabola?????:)

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0well, it didnt give me a focus it just gave me the P at (2,4)

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0it also says the parabola is y=x^2 so...um the p, 1/4

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0@lilsis76 focus of x2 = 4ay is(0,a) so compare it with x^2=y this implies 4a=1 or a=1/4 so it is(0,1/4).k

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0now you have 2 points p(2,4) and focus f(0,1/4) so can u draw a line???????????

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0so thats ur focal chord any chord passing through focus is called focal chord:)

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0let me write that down

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0did i make the line right?

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0ya you make it right:) sry i didn't noticed ur reply:( @lilsis76

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0haha its okay. but thank u for letting me know. Okay whats next what do i have to do?

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0dw:1352586259141:dw now what is the coordinate of any point on parabola?????

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0wait, its a normal looking parabola with the point (0,0) right? thats how you got that parabolas shape?

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0im sorry im kinda new to this lol

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0since you said any point. ill go to the left. the Q would be P's opposite and be .. 2,4? right?

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0well it is not what i asked i asked general form it is(x,x^2) :) as PFQ is a straight line so slope of PF=FQ now find their slopes...........when u solve this completely i will tell you a short method:)

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0okay. im trying to do PF, is that ...getting the 2*1/4?

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0hmm... let me try again

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0i got..... 4  1/4 / 20

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0dw:1352587321957:dw i dont know how to work out the fraction and whole number

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0slope m=dw:1352587256238:dw solve for x i just compare the two slopes:)

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0@lilsis76 is it value of x?????????

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0oh. well then imma say yes it is then

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0dw:1352587871193:dw

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0how did you get the 13/8?

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0dw:1352588075547:dw so x=1/8 or 2

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0coordinates are (x,x^2) from fig x<0 x cannot be =2 Q=(1/8,1/16)

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0and the 2, did you just add the 1/8 th twice to get 1/16?

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0now shortcut method:) Let y2 = 4ax be the equation of a parabola and (at^2, 2at) a point P on it. Suppose the coordinates of the other extremity Q of the focal chord through P are (at1^2, 2at1). then t1=1/t:) so dw:1352588333605:dw

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0no @lilsis76 as the coordinates are(x,x^2)

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0@lilsis76 did u got it?????????

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0kinda, not really. okay well i ended up getting the  1/8 for x, i plug it in right?

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0ok i got 8x+1 an x2, x= 1/8, x=2

Aperogalics
 2 years ago
Best ResponseYou've already chosen the best response.0now go ahead for shortcut:)

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0the shortcut u gave me?

lilsis76
 2 years ago
Best ResponseYou've already chosen the best response.0anywho, i did the math cuz shortcut got me lost. i have x = 1/8 and x=2
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