Arcsin (ctg п/4)= cos(arcsin(-1/2)-arcsin1)=
Решение смотри на фотографии
Arcsin(ctg(π/4))=arcsin(1)=π/2 cos(arcsin(-1/2)-arcsin(1))=cos(2π/3-π/2)=cos(4π/6-3π/6)=cos(π/6)=√3/2