Lung cancer is the top cause of cancer deaths in both men and women. But this wasn't always the case. Prior to the widespread use of mechanical cigarette rollers, lung cancer was rare. Today, smoking causes nearly 9 out of 10 lung cancer deaths, while radon gas, pollution, and other things play a smaller role.
From Wikipedia, the free encyclopedia. A plane symmetry is a symmetry of a pattern in the Euclidean plane: that is, a transformation of the plane that carries any directioned lines to lines and preserves many different distances. If one has a pattern in the plane, the set of plane symmetries that preserve the pattern forms a group. The groups that arise in this way are plane symmetry groups and are of considerable mathematical interest. A symmetry plane is a three-dimensional object's symmetry axe. There are several kinds of plane symmetry groups: Reflection groups.
Symmetry comes from a Greek word meaning 'to measure together' and is widely used in the study of geometry.Mathematically, symmetry means that one shape becomes exactly like another when you move it in some way: turn, flip or slide.For two objects to be symmetrical, they must be the same size and shape, with one object having a different orientation from the first.here can also be symmetry in one object, such as a face. If you draw a line of symmetry down the center of your face, you can see that the left side is a mirror image of the right side. Not all objects have symmetry; if an object is not symmetrical, it is called asymmetric.