решение. 1. ri=2*r; rii=r/2; ri/rii=4; не надо ни о какой площади сечения говорить. два куска проволоки содинили последовательно, получили ri=2*r; два куска той же проволоки соединили параллельно, получили rii=r/2; ну, а теперь раздели первое на второе!
а теперь общий случай: ri=r*n; rii=r/n; ri/rii=n^2; кусок проволоки разрезали на n одинаковых кусков. сначала эти куски соединяют последовательно: ri=r*n; затем соединяют параллельно rii=r/n; ну и дели первое на второе и делай выводы.
But the weather has definitely failed me. Winter did not want to leave, even at the end of March it was very frosty.
But still, vacations are a vacation and my mood was festive every day.
I managed to go several times to the cinema, a couple of times I was visiting friends that I rarely meet in my daily life - they live far away and after school they do not go to visit them comfortably, and on weekends they always find something for me, caring parents .
I spent the spring break just fine. There have been many interesting events. For example, I went to the movies with my sister, I really liked it, and we will definitely go there again. And, my friend had a birthday, and we celebrated it in a cafe. Then we twice went to competitions in the Palace of Sports that would cheer for our team