Normals determine whether a given triangle face is lit.

法线会判断指定的三角形表面是否会被照亮。

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For a triangle in a given 3-d mesh, the order in which the triangle's vertex positions are specified determines whether the triangle face is a front or back face.

如果是指定的3 - d网状结构中的三角形，三角形顶点位置的指定顺序会决定三角形表面是正对面或背对面。

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Each face is an equilateral triangle and three faces meet at each vertex.

每一个面是正三角形并且于每一个顶点处有三个面相交。

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During the operation, teams of doctors grafted a triangle of tissue including a nose, lips and chin onto the face of the 38-year-old divorced mother of two teenaged daughters, who had been attacked by a Labrador and whose name has not been disclosed.

CNN: Face transplant woman thanks team

His face was smeared with sandalwood, and he wore a loose-fitting silk shirt through which a dark triangle of chest hair stuck out.

NEWYORKER: The Elephant