х+14= 20+14
х+14=34
х= 34- 14
х=20
20+14 =20+14
14=14
2arcctg1=2*π/4=π/2
arcsin1=π/2
arcctg0=π/2
cos(2arcctg1-arcsin1+arcctg0)=cos(π/2-π/2+π/2)=cos(π/2)=0