Answer:
[tex]sin(90-x)=cos(x)[/tex]
So,
[tex]sin(a-b)=sin(a)cos(b)-cos(a)sin(b)[/tex]
[tex]sin(90\º-x)=sin(90\º)cos(x)-cos(90\º)sin(x)[/tex]
Once, [tex]sin90\º=1[/tex] and [tex]cos(90\º)=0[/tex]
[tex]sin(90\º-x)=1cos(x)-0sin(x)[/tex]
[tex]sin(90\º-x)=cos(x)[/tex]
