As many or as few as you like.
The measurement of the angle in a two-dimensional shape is the amount of rotation between two intersecting lines, typically measured in degrees.
The inside of a two-dimensional shape is called its interior.
the difference between a two dimensional shape and and a solid is that a two dimensional shape is plane and a solid you can see the whole shape a the inside.
A rhombus is a two dimensional (plane) shape that is bounded by four congruent lines. If these lines meet at right angles, then the shape is a square which is a special type of rhombus.
Lines are one-dimensional objects but they can be in 2-dimensional - or even 20-dimensional) space.
It is a plane shape, ie it is 2-dimensional or flat. It is a closed shape defined by four straight lines that meet at four points, two lines at each point.
An octagon is a two-dimensional shape.
A two dimensional shape would have 17 sides. For a three dimensional shape - assuming that sides are faces - the answer depends on the shape itself.
A parallelogram is a plane, or two-dimensional shape that is bounded by four straight lines which form its sides. Each pair of opposite sides consists of parallel and congruent (same length) lines.
Flat shapes such as polygons are two-dimensional.
A semi-circle is a two dimensional shape.
Zero. Lines are one-dimensional and squares are two-dimensional, so they are not comparable.