Answer :
[tex]\boxed{\sf cos(A+B)=cosAcosB-sinAsinB}[/tex]
Now
[tex]\\ \sf\longmapsto cos(x+1)[/tex]
- A=x
- B=1
[tex]\\ \sf\longmapsto cosxcos(1)-sinxsin(1)[/tex]

[tex]\boxed{\sf cos(A+B)=cosAcosB-sinAsinB}[/tex]
Now
[tex]\\ \sf\longmapsto cos(x+1)[/tex]
[tex]\\ \sf\longmapsto cosxcos(1)-sinxsin(1)[/tex]