Since the objective is " Solving the real-life problems in the co-sinus function," we connected with music and co-sinus and made students link the co-sinus in real life! Moreover, students often have difficulty with this, which may attract even more interest and motivation to learn about the subject. Our primary goal is to convey that mathematics is a field we will encounter everywhere. Music, from the most basic to the most complex, contains various containment structures (music and mathematics)