What is the difference between 1st angle and 3rd angle projection

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1st and 3rd angle projection are two methods of representing a 3D object on a 2D surface.

In 1st angle projection, the object is placed in front of the viewing plane and the planes of projection are between the object and the viewer.
In 3rd angle projection, the object is placed behind the viewing plane and the planes of projection are between the object and the viewer.
In 1st angle projection, the top view is placed above the front view while in 3rd angle projection, the top view is placed below the front view.
1st angle projection is commonly used in Europe while 3rd angle projection is commonly used in the United States.
The symbol for 1st angle projection is a square with a dot in the center while the symbol for 3rd angle projection is a square with three dots in a triangular formation.

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