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Ellipses. Topic 11.3. Definitions. Ellipse: set of all points where the sum of the distances from the foci is constant Major Axis: axis on which the foci lie; the longer axis of symmetry Minor Axis: the shorter axis of symmetry. Two Standard Equations. Horizontal Ellipse: Foci:
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Ellipses Topic 11.3
Definitions • Ellipse: set of all points where the sum of the distances from the foci is constant • Major Axis: axis on which the foci lie; the longer axis of symmetry • Minor Axis: the shorter axis of symmetry
Two Standard Equations • Horizontal Ellipse: • Foci: • Vertical Ellipse: • Foci:
Writing in Standard Form • Complete the square for both the x-terms and y-terms and move the constant to the other side of the equation • Divide all terms by the constant
Example: Group terms Complete the square Simplify each group Divide by constant
Graphing the ellipse • Put equation in standard form • Graph the center (h, k) • Graph the foci (look at the equation to determine your direction) • Graph a units and –a units from the center to get the end points of major (horizontally if under x, vertically if under y) • Graph b units and –b units from the center to get the end points of minor (vertically if under x, horizontally if under y) • Connect the end points!
Example: 1) Graph Center 2) Graph Foci . 3) Graph Endpoints of both axis . 4) Graph Ellipse
Answer the following for the last problem • a = b = • 1. horizontal or vertical • 2. center/shift • 3. vertices • 4. length major axis • 5. length minor axis • 6. foci
You Try!Write the following equation in standard form, then graph it.