What does complementarity mean?

Answer 1

"Complementarity" may be "the property of being complementary" or something like that. In geometry, two angles are said to be complementary if their sum is equal to 90 degrees. For example, 30o and 60o are complementary because 30o + 60o = 90o. There are also a number of other applications of the term "complementary" in mathematics. One more might be its use in probability and statistics. If the sum of two probabilities is one, they are said to be complementary. Here's a killer example: On a given coin toss, the probability of a head coming up is complimentary to the probability of a tail coming up. The actual formula is P(A) + P(B) = 1 In a quickie review of probability as it is used here, if something cannot possibly happen, the probability of it happening is zero. If something absolutely will occur without any possibility of anything else happening, the probability of that event happening is one. So probabilities range between zero and one (inclusive). The probability of a head coming up in a coin toss is one 1 in 2, or 50%, or 0.5 (speaking in mathematical terms of probability). The probability of a tail is the same (0.5). Let's just do a quick math thingie with that and get it to lock in: Probability of a head = Ph = 0.5 Probability of a tail = Pt = 0.5 Ph + Pt = 0.5 + 0.5 = 1.0 Ph and Pt are said to be complementary, since Ph + Pt = 1.0