Difference between first angle projection and third angle projection

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Accepted Answer

First angle projection and third angle projection are two methods of creating orthographic projections of a 3D object.

First angle projection is commonly used in Europe and Asia, while third angle projection is commonly used in North America.
In first angle projection, the object is placed in front of the viewing plane and the views are created by projecting lines from the object onto the plane.
In third angle projection, the object is placed behind the viewing plane and the views are created by projecting lines from the object through the plane.
The symbol used to indicate the projection method is different for first and third angle projection.
First angle projection symbol: a square with a cross inside, while third angle projection symbol: a square with three arrows pointing towards it.

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