A friend 's birthday . New Year is approaching . Getting a passport , new home - all the happy events are countless. I have before me the question - what to give friends and family ? Gift - a manifestation of good feelings : friendship, love, deep respect , he must testify that the person making the choice to think about the taste and desires of the person to whom it is intended. In the present, as in a mirror , reflects the level of culture who gives - his generosity or stinginess , intelligence and humor , frivolity and lack of taste . Not accepted without gifts , even small, inexpensive , go for a visit to a family where there are small children . Cleverly chosen gift can have a big influence on the interests of the teenager. Set of paints and crayons can awaken interest in painting . The book on archeology , life scientists, artists can help in choosing a career . For a girl with whom you are meeting for the lady of the house, where you are invited to visit, a bouquet of flowers is always appropriate . Friend with whom you have not seen , will be pleasantly surprised when you present to him any original souvenir . It is not necessary that the gift was expensive or practical thing. Very practical approach to the evaluation of the presented does not decorate the person. One day a girl gave handmade , unique shape vase , and she took it as a cheap pot , as the vase was not crystal . And the other - a bouquet of wild flowers , gathered for her , covered in dew in the morning aroma of meadows, and she is happy
1) а) 3 однієї вершини п'ятикутника можна провести 2 діагоналі.
6) 3 однієї вершини дев'ятикутника можна провести 6 діагоналей, в) 3 однієї вершини n-кутника можна провести (п - 3) діагоналі.
2) В п-кутнику з однієї вершини можна провести (л - 3) діагоналі. Врахувавши, що вершин п і кожна діагональ рахується двічі, отримуємо, що всього в ті-кутнику можна провести п(п - 3): 2 діагоналей.
а) П'ятикутник: 5-(5-3):2 = 5-2:2=10:2 = 5 діагоналей;
б) дев'ятикутник: 9 * (9 - 3): 2 = 9 * 6 : 2 = 54 : 2 = 27 діагоналей;
в) n-кутник: п(п — 3): 2 діагоналей.
ответ к заданию по русскому языку
