Question

18 корень 2 sin a* ctg (пи-а), если cos a=корень из2/2

Answer 1

$18 sqrt{2} sin alpha *ctg( pi - alpha )=18 sqrt{2}sin alpha *(-ctg alpha )= \ \ =-18 sqrt{2}sin alpha * frac{cos alpha }{sin alpha }=-18 sqrt{2}cos alpha \ \ -18 sqrt{2}* frac{ sqrt{2} }{2}=- frac{18*2}{2}=-18$