could somebody take a look at this? I got random guest answered and then I got a link with its description in russian that I cant open.
https://web2.0calc.com/questions/let-be-an-angle-such-that-p-is-the-terminal-point-of_1#r4
See https://web2.0calc.com/questions/let-be-an-angle-such-that-p-is-the-terminal-point-of_1#5
+163 
