A square has four; a pentagon has five.
triangles
no they dont
yes
If you're talking about convex polygons with equal sides (eg. equilateral triangles, squares, pentagons, hexagons, etc.), then the relationship is a very direct one. In those cases, there are as many lines of symmetry as there are points in the polygons. A triangle has three lines of symmetry, a square has four, a pentagon five, etc.
yes
A circle or sphere has an infinite number of lines of symmetry.
In general, a square. A square always has 4 lines of symmetry. A pentagon need not have any. Only a regular pentagon can have 5 lines of symmetry. But if you created pentagons from sides with random lengths then, assuming the pentagons existed, only a tiny fraction would be regular: most pentagons would have no axes of symmetry.
The square is the only one I can think of. The lines are vertical, horizontal, and both diagonals.
Most parallelograms do not have any lines of symmetry. The only parallelograms that can have lines of symmetry are squares, rectangles, and rhombuses.
Squares.
Yes
Yes. Some example of this are:Rectangles (at least 2 lines of symmetry)Squares (4 lines of symmetry)Rhombuses (at least 2 lines of symmetry)