Lewis structure. The Lewis structures, also called Lewis-dot diagrams or electron dot diagrams are pictures that show the bonding between a pair of electrons and the atoms of a molecule. Each dot represents one electron. Two dots side by side represent a lone pair of electrons.
Right angles are like corners and measure 90Â°. Acute angles are smaller than 90Â°. Obtuse angles are larger than 90Â°, but less than 180Â°. And straight angles are 180Â°, which is where the two lines go in the same direction and become like a single straight line. And that's all there is to it: each of the four types of angles in mathematics.
Acute and obtuse angles are smaller and respectively greater than right. Usually, obtuse angles are taken to be smaller than straight, in which case the angles that exceed the straight angle are said to be reflex. A reflex angle so big as to have its two sides overlap is full. (A dynamic illustration is available elsewhere.) The sum of two acute angles is either acute, right or obtuse. The sum of an obtuse and an acute angle, or of three acute angles, may be reflex. The existence (or admittance) of reflex angles kills all hope that the interior of an angle may be determined from its sides in a natural way. Handpicking the interior and appending it to the definition almost solves the problem.