Чи можуть одночасно виконувати рівності:
а) tg=5 і ctg a=1/5
б) sin a= 1/4 і cos a=3/4

Пропорция - это верное равенство двух отношений.х : у = 4 : 9                   у : z  = 15 : 2 2/3В первой пропорции у = 9, во второй у = 15. НОК (9 и 15) = 45.45 : 9 = 5 - доп. множ. к первой пропорции 45 : 15 = 3 - доп. множ. ко второй пропорцииВнесём изменения:х : у = (4*5) : (9*5)       у : z = (15 * 3) : (2 2/3 * 3)х : у = 20 : 45               у : z = 45 : (8/3 * 3)  Получаем: х : у : z = 20 : 45 : 8219 : (20 + 45 + 8) = 219 : 73 = 3 - одна частьх = 20 * 3 = 60у = 45 * 3 = 135z = 8 * 3 = 24х + у + z = 60 + 135 + 24 = 219 - сумма трёх слагаемыхответ: х = 60; у = 135; z = 8. 

person.Travelling is one of the most effective methods of dealing with stress, personal problems and one of the best ways to change their lives. Travel promotes physical and emotional hardening. The journey can make each person, for reasons of need:work, school, on the territory of another country, to visit relatives or relax.They have to think of a plan journey. Tourism - job or even a lifestyle, when people go to other countries to learn more about the culture and countries. Tourism takes the money and gives impressions. The journey generally short, tourism is a long process, the trip will likely last for months. Tourist implies a thirst for knowledge. Traveler, unlike the tourist takes responsibility for themselves, relying on their strength, knowledge, experience. Travellers choose their route, decide on transportation, country, places to visit.They turn your vacation into an unforgettable adventure.Being a traveler is much more complicated than a tourist, but much more interesting!