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9.2 Parabolas. Emerald Seing. A parabola is defined in terms of a fixed point, the focus , and a fixed line, the directrix . PF=PD meaning that any point on the parabola to the focus is equal to the shortest distance from that point to the directrix. Finding The Equation.
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9.2 Parabolas Emerald Seing
A parabola is defined in terms of a fixed point, the focus, and a fixed line, the directrix. PF=PD meaning that any point on the parabola to the focus is equal to the shortest distance from that point to the directrix.
Horizontal Directrix • The parabola will open either up or down • The equation will have Y by itself on one side • The line of the directrix will cross the Y-axis • The axis of symmetry will be on the Y-axis • Y=… Vertical Directrix • The parabola will open either right or left • The equation will have X by itself on one side • The line of the directrix will cross the X-axis • The line of symmertry will be on the X-axis • X=…
These equations apply to all parabolas who’s centers are not located at (0,0).
Example Two