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.
A right angle is one whose measure is exactly 90Â°. On a drawing the symbol can be used to label two rays or segments as perpendicular (at right angles). In symbols we write that one line or segment is perpendicular to another using the symbol . An obtuse angle is one whose measure is strictly between 90Â° and 180Â°.