For the best answers, search on this site https://shorturl.im/8g1Rz. Before addressing the problem, consider a regular pentagon with unit sides. Draw a diagonal d and observe that d = 2*cos(36) from one side and d = 2*cos(72) + 1 from the other so that Â½ = cos(36) - cos(72) = cos(36) - (2cosÂ²(36)-1).
Ionic compound. In chemistry, an ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. Usually, the positively charged portion consists of metal cations and the negatively charged portion is an anion or polyatomic ion.hus, in an ionic bond, one 'bonder' must have a positive charge and the other a negative one. By sticking to each other, they resolve, or partially resolve, their separate charge imbalances. Positive to positive and negative to negative ionic bonds do not occur. Chemical compounds are never strictly ionic.
An ionic bond is a bond between ions with opposite charges. Cations (positively charged ions) cannot exist without anions (negatively charged ions). An electron released by an atom to from a cation must be accepted by another atom to form an anion. Cations and anions are formed in many chemical reactions by the transfer of one or more electrons from one element to another. Ionic bonds are formed by a strong attraction between positive and negative ions. Characteristics of Ionic compounds. Some important characteristics of ionic compounds are as follows. 1. Ionic compounds are hard and rigid due to strong forces of attraction between the oppositely charged ions.