抛物线的丹德林球模型演示
2019-05-16 15:26
本范例通过丹德林球模型直观演示抛物线的几何定义与性质。在圆锥截面中，通过构造内切球与截平面及圆锥表面的切点，展示焦点、准线以及抛物线上任意一点到焦点与准线距离相等的几何本质。适合立体几何与解析几何教学，帮助理解圆锥曲线的空间构造。
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<coords x="2.5290822877054113" y="0" z="3.4719794352158706" w="1"/>
<pointSize val="7"/>
</element>
<command name="Segment">
<input a0="E" a1="G"/>
<output a0="EG"/>
</command>
<element type="segment3d" label="EG">
<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>