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.
Line Symmetry. Basically, a line of symmetry is a line that divides a figure into two mirror images. The figure is mapped onto itself by a reflection in this line. A set of points has line symmetry if and only if there is a line, l, such that the reflection through l of each point in the set is also a point in the set.(May also be referred to as reflectional symmetry.). Certain figures can be mapped onto themselves by a reflection in their lines of symmetry.asically, a figure has point symmetry when it looks the same when up-side-down, (rotated 180Âº), as it does right-side-up. The number of positions in which the rotated object appears unchanged is called the order of the symmetry.