How are the concepts of dominant, recessive, heterozygous, and homozygous related to the hardy - weinberg equation?/?

The equation is p² + 2pq + q² = 1, and p + q = 1, where p is the frequency of the dominant allele in a population and q is the frequency of the recessive allele in a population.

The concepts named above are described by the equation, by which we can calculate the frequency of the dominant and recessive alleles. Then, the homozygous frequencies can be calculated as the squares of the allele frequencies, and the heterozygous frequency can be calculated as 2 * (frequency of dominant allele) * (frequency of the recessive allele).