Dandelin Spheres Model of a Parabola
2019-05-16 15:26
This applet visually demonstrates the geometric definition and properties of a parabola using the Dandelin spheres model. By constructing an inscribed sphere tangent to the cutting plane and the cone, it illustrates the focus, directrix, and the equidistant property. Ideal for solid and coordinate geometry education.
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Conic Sections | GeoGebra Book
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<show object="true" label="false" ev="4"/>
<objColor r="0" g="153" b="255" alpha="0"/>
<layer val="0"/>
<labelMode val="0"/>
<selectionAllowed val="false"/>
<lineStyle thickness="5" type="0" typeHidden="2"/>
<outlyingIntersections val="false"/>
<keepTypeOnTransform val="true"/>
</element>
<command name="Segment">
<input a0="O" a1="G"/>
<output a0="OG"/>
</command>
<element type="segment3d" label="OG">
<show object="true" label="false" ev="4"/>
<objColor r="192" g="192" b="192" alpha="0"/>
<layer val="0"/>
<labelMode val="0"/>
<selectionAllowed val="false"/>
<lineStyle thickness="5" type="0" typeHidden="2"/>
<outlyingIntersections val="false"/>
<keepTypeOnTransform val="true"/>
</element>
<expression label="text2" exp=""Cone""/>
<element type="text" label="text2">
<show object="true" label="false" ev="37"/>
<objColor r="125" g="125" b="255" alpha="0"/>
<layer val="0"/>
<labelMode val="0"/>
<absoluteScreenLocation x="22" y="79"/>
<ggbscript val="SetValue(showCone, !showCone)"/>
</element>
<element type="boolean" label="showCone">
<value val="true"/>
<show object="false" label="true"/>
<objColor r="0" g="0" b="0" alpha="0"/>
<layer val="0"/>
<labelMode val="0"/>
<checkbox fixed="true"/>
</element>
</construction>
</geogebra>