Bro and sister Please bantu aku dong tugasnya susah banget Cuma nomor 19 dong please bantuannya

c maaf kalau jawaban saya ini salah

AC/(sin B) = AB/(sin C)
10/(sin 30°) = 15/(sin C)
2/(1/2) = 3/(sin C)
4 = 3/(sin C)
Sin C = 3/4 = de/mi => sa = √(4^2 - 3^2) = √(16 - 9) = √7
Cos C = sa/mi = √7/4 = (1/4)√7