A flat surface with an infinite length and width but no depth is called a plane.
A surface that has length and width.
A plane
2D is flat, determined by a length and a width. 3D is determined by having a length, width, and height. 4D is determined by having a length, a width, a height, and a dimension in time.
2d is a flat shape with only 2 dimentions (width & length) 3d is a shape with 3 dimensions (width, length and depth)
Length x width = square footage
Plane figures are those that have a length and width but no height. they are two dimensional or flat.
Multiply length in feet by width in feet to get square feet.
If the bar is a three dimensional object it will have some thickness. Then, assuming it is oblong in shape and knowing its length, width and thickness: Surface_area = 2 x (length x width + width x thickness + thickness x length)
A 3D figure has length x width x depth. It becomes a 2D figure once the removed surface is laid flat, having then only length x width. Another name is "Plane Figure."
Length relates to the distance between two points. Area is the width of a flat object multiplied by its height. Volume is the width times the height times the length of a 3-dimensional object.
A rectangular prism has three dimension: its length, width and height. A flat and long prism is one whose height is small and length is large.