Skull with crossed bones back in red circle about dangerous

>This article is about the shape and mathematical concept of circle; for other meanings, see Circle (disambiguation). In Euclidean geometry, a circle is the set of all points at a fixed distance, called the radius, from a fixed point, called the centre (center). The points can only be those that are part of a conic section; within the set of a plane bisecting a cone. Circles are simple closed curves, dividing the plane into an interior and exterior. Sometimes the word circle is used to mean the interior, with the circle itself called the circumference. Usually however, the circumference means the length of the circle, and the interior of the circle is called a disk or disc. See more at Wikipedia.org...

>For other uses, see Red (disambiguation). Red is a color at the lowest frequencies of light discernible by the human eye. Red light has a wavelength range of roughly 630-760 nm.Red is an additive primary color, complementary to cyan. It was once considered to be a subtractive primary color, and is still sometimes described as such in non-scientific literature; however, the colors cyan, magenta and yellow are now known to be closer to the true subtractive primary colors detected by the eye, and are used in modern color printing. See more at Wikipedia.org...