Question

1) ctg^x=3
2) cos(x-3pi/2)=0

Answer 1

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