A line has 180 degrees rotational symmetry.
Line symmetry.
Yes
You cannot have one parallel line. There must be another line that it is parallel to. Also, 1 symmetry is meaningless - you can have one axis of symmetry or rotational symmetry of order one. The answer will depend on which one it is.
A figure that has rotational symmetry but not line symmetry is a figure that can be rotated by a certain angle and still look the same, but cannot be reflected across a line to create a mirror image of itself. An example of such a figure is a regular pentagon, which has rotational symmetry of 72 degrees but does not have any lines of symmetry. This means that if you rotate a regular pentagon by 72 degrees, it will look the same, but you cannot reflect it across any line to create a mirror image.
Yes. Any equilateral shape can have both rotational and line symmetry.
A semicircle.
circle
A line segment would have rotational symmetry.
Yes, it is possible to have a shape that has a line of symmetry but does not have rotational symmetry. An example is the letter "K", which has a vertical line of symmetry but cannot be rotated to match its original orientation.
How about an isosceles trapezoid
The letters S, N, Z, for example.
A triangle........I think
Parrallelogram (it has rotational symmetry but no lines of symmetry)
The letters H and Z have both line symmetry and rotational symmetry
It has line symmetry (straight down the center) but not rotational symmetry.
A line has rotational symmetry of order 2.