I'd like to tell you about my best friend. His name is Nikita. He is thirteen years old. We have been friends for three years, since the time when Nikita's family moved to our city and he became my classmate.
Nikita is a bit taller than me but he is as slim as I am. He has got short wavy dark hair and brown eyes. I think he is quite fit and strong, in fact he is very good at our Physical Education activities. By the way his favourite school subjects are Geography and History. Nikita says he wants to be an explorer.
My friend is a good listener and he is always ready to help me in difficult situations. I know for sure that he is able to keep secrets.
What I like most of all is that Nikita is a real optimist with a good sense of humor. I hope we'll be friends forever.
cos(x/3-п/6)=-корень из 3/2
х/3-п/6=+-п-п/3+2пк
х/3-п/6=+-4п/3+2пк
1) х/3=3п/2+2пк
х=3п+6пк
2) х/3=-7п/3+2пк
х=-7п+6пк