Question

ctg x = 2,05

sin²x = 1

cos²x = 1/2

Answer 1

1)ctgx=2,05⇒x=arcctg2,05+πn,n∈z
2)sin²=1
(1-cos2x)/2=1
1-cos2x=2
cos2x=-1
2x=π+2πn,n∈z
x=π/2+πn,n∈z
3)cos²x=1/2
(1+cos2x)/2=1/2
1+cos2x=1
cos2x=0
2x=π/2+πn,n∈z
x=π/4+πn/2,n∈z