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.
Reflection and rotational symmetry together A shape can have no lines of symmetry, but its order of symmetry must be at least one. For regular polygons, the number of lines of symmetry is equal to the order of rotational symmetry, and both are equal to the number of sides.For example, a pentagon has five sides, five lines of symmetry and an order of rotational symmetry of five.The order of rotational symmetry of a shape is always equal to or greater than the number of lines of symmetry it has. Consider the shapes below.here is a number called the order of rotational symmetry. This is how many times the shape looks the same as it is rotated through 360Â°. Shown below are the stages of rotating an equilateral triangle through 360Â°. Each triangle is rotated 30Â° clockwise from the one to its left.