document.write( "Question 1032247: 1. Use the focus-directrix definition of a parabola to answer the following questions.\r
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document.write( "1) How would the shape of the parabola change if the focus were moved up, away from the directrix? How would we describe p?
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document.write( "2) How would the shape of the parabola change if the focus were moved down, toward the directrix? How would we describe p?
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document.write( "3) How would the shape of the parabola change if the focus were moved down, below the directrix?\r
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document.write( "2. Given:\r
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document.write( "y = 3x^2\r
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document.write( "1) Write the equation of a parabola that contains the point (2, ‒12) that is congruent to the parabola that is given. Describe the series of transformations that would move the given parabola to your parabola.\r
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document.write( "2) Write the equation of a parabola that contains the point (0, 8) that is congruent to the parabola that is given. Describe the series of transformations that would move the given parabola to your parabola.\r
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document.write( "3) Write the equation of a parabola that is similar (not congruent) to the given parabola that does NOT contain the point (0, 0), but does contain the point (2, 2).\r
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document.write( "Note: Please show all work so that I can understand how to do the problem. Thank you.
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Algebra.Com's Answer #647068 by KMST(5328)![]() ![]() You can put this solution on YOUR website! PROBLEM !: \n" ); document.write( "1. The focus-directrix definition of a parabola with axis parallel to the y-axis and vertex at the origin leads to the equation \n" ); document.write( " \n" ); document.write( "for a parabola with directrix \n" ); document.write( "It is valid (and useful) to think of the problem based on such a parabola, with \n" ); document.write( "\n" ); document.write( "1) Moving the focus \"up, away from the directrix\" means that \n" ); document.write( "away from the directrix was up, meaning that \n" ); document.write( " \n" ); document.write( "As we move F up, the square expands, and the parabola opes wider: \n" ); document.write( " \n" ); document.write( "How would we describe \n" ); document.write( " \n" ); document.write( "2) How would the shape of the parabola change if the focus were moved down, toward the directrix? How would we describe p? \n" ); document.write( "We reverse the motion, from the blue parabola to the green one. \n" ); document.write( "The parabola gets \"taller, stretched vertically, hugging its axis tighter, and \n" ); document.write( "\n" ); document.write( "3) How would the shape of the parabola change if the focus were moved down, below the directrix? \n" ); document.write( "You have to jump over the directrix, of course. The focus cannot be on the directrix, with \n" ); document.write( "You have flipped the parabola upside down, so it would be a frown rather than a smile. It now open downs, with a \n" ); document.write( " \n" ); document.write( "PROBLEM 2: \n" ); document.write( "A generic parabola, with vertex at the origin, axis on the y-axis, and opening up, with focus \n" ); document.write( " \n" ); document.write( "Changing the sign of \n" ); document.write( "Horizontal and/or vertical translations of a parabola, with vertex at the origin, and axis on the y-axis would yield other parabolas that we would call \"congruent\" to each other, because we can superimpose them by using those translations. \n" ); document.write( "Those parabolas have an equation of the form \n" ); document.write( " \n" ); document.write( "where \n" ); document.write( "and \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "So, for \n" ); document.write( "1) We can get \"a parabola that contains the point (2, ‒12) that is congruent to the parabola that is given\" by translating the vertex to the point (2, ‒12) . \n" ); document.write( "That means \n" ); document.write( "which would give us \n" ); document.write( " \n" ); document.write( "That parabola could be obtained easily by \n" ); document.write( "translating \n" ); document.write( "We can find an unlimited number of different examples of \"a parabola that contains the point (2, ‒12) that is congruent to the parabola that is given,\" but that would require more computation. \n" ); document.write( "For parabolas opening up, they would need to \n" ); document.write( "have an equation of the form \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "2) Similarly, \n" ); document.write( "is \"a parabola that contains the point (0, 8) that is congruent to the parabola that is given\". translating up by 8 units \"would move the given parabola to\" \n" ); document.write( " \n" ); document.write( "3) All parabolas are similar, meaning that if you change the scale factor \n" ); document.write( "(making the units on both axes larger or smaller by the same factor), \n" ); document.write( "you can superimpose them. \n" ); document.write( " \n" ); document.write( "Since \n" ); document.write( "Using the same scale, you see that they are clearly not congruent: \n" ); document.write( " \n" ); document.write( "However, when we scale down appropriately, we see that they would superimpose: \n" ); document.write( " |