Simplify (sin42degrees)cos38degrees-(cos42degrees)sin38degrees

Question

This is for my trig class, thanks for the help!

Answer 1

 This is formula for Sin ( A - B) = Sin A Cos B - Cos B Sin A

 

     In this case

 

     A = 42° , and B = 38°

 

    The formula reduces to Sin ( 42° - 38° ) = Sin 4°