1) ctg^x=3 2) cos(x-3pi/2)=0
1) ctgx = 3 x = arcctg 3 + pi×n 2) cos (x - 3pi/2) = 0 x - 3pi/2 = 0 x = 3pi/2 x = +- arccos 3pi/2 + 2pi×n