Habralyudi! I call for help! Today at 16.00 Moscow time, I pass the entrance to the Polytechnic. Please scold me for an hour :) PS THANKS :) Guys, this method works :) I’ll know the results on Friday. In general, I was lucky, I got a smart person hooked to me :) And I managed to make 4 of 5 examples :) I managed to peek at the solution of someone else's problem, and it was not so difficult to remember formulas :) Damn, how easy it is to forget sin, cos and log in 2 years :) Once again, thanks for the support!