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A long strip of cardboard of constant width is folded as shown in the figure int

ID: 1592838 • Letter: A

Question

A long strip of cardboard of constant width is folded as shown in the figure into side 1 that has a short length, side 2 with a medium length and side 3 with a long length.

Note: A,b,c,d are large, e,f,g,h are medium, and i,j,k,l are small

1a) Identify which of the vectors shown best represents the normal vector for side 1 of the folded cardboard.

1b) Identify which of the vectors shown best represents the normal vector for side 2 of the folded cardboard.

1c) Identify which of the vectors shown best represents the normal vector for side 3 of the folded cardboard.

2 2 3 3 Perspective Front View

Explanation / Answer

Since the card board has a open shape there is no direction to inside or uotside to a enclosed shape, therefore, each side must has two normal vectors.

Remember that the normal vector must be proportional to the size of the area and perpendicular to the surface.

1a) The side 1 is a small side, therefore the normal vectors are in i,j,k,l. In that vectors only k and l are perpendiculars to the surface. The normal vectors are  k and l

1b) The side 2 is a medium side, therefore the normal vectors are in e,f,g,h. In that vectors only e and f are perpendiculars to the surface. The normal vectors are e and f

1c) The side 3 is a medium side, therefore the normal vectors are in a,b,c,d . In that vectors only c and d are perpendiculars to the surface. The normal vectors are c and d