sinx=4sinx+y)
--->sin[(x+y)-y]=4sin(x+y)
--->sin(x+y)cosy-cos(x+y)siny=4sin(x+y)
--->sin(x+y)(cosy-4)=cos(x+y)siny
--->sin(x+y)/cos(x+y)=siny/(cosy-4)
--->tan(x+y)=siny/(cosy-4)
sinx=4sinx+y)
--->sin[(x+y)-y]=4sin(x+y)
--->sin(x+y)cosy-cos(x+y)siny=4sin(x+y)
--->sin(x+y)(cosy-4)=cos(x+y)siny
--->sin(x+y)/cos(x+y)=siny/(cosy-4)
--->tan(x+y)=siny/(cosy-4)