Question 869639
I would use the trigonometric identity
{{{sin(A+B)=sin(A)*cos(B)+cos(A)*sin(B)}}}
and the fact that {{{sin(-B)=-sin(B)}}} .
 
{{{sin(49^o)cos(11^o)-cos(49^o)sin(11^o)=sin(49^o)cos(11^o)+cos(49^o)(-sin(11^o))=sin(49^o)cos(-11^o)+cos(49^o)sin(-11^o)=sin(49^o+(-11^o))=highlight(sin(49^o-11^o))=highlight(sin(38^o))}}}
 
NOTE:
Someone may say to use
{{{sin(A-B)=sin(A)*cos(B)-cos(A)*sin(B)}}} ,
but that means one more formula.
I do not believe in memorizing, so I just rediscover the formulas with a + sign each time I need one of them.