jawab soal tentang aturan sinus

∠A = 30° , ∠C = 105°
∠B = 180 - ( 30 + 105 )
      = 45°
BC = 7
AC = ........?
jawab :
AB/sinC = BC/sinA = AC/sinB
AB/sin105° = 7/sin30° = AC/sin45°
7/sin30° = AC/sin45°
7/(1/2)   = AC/(1/√2)
1/2AC    = 7/√2
AC        = 14/√2
AC        = 14√2/2
AC        = 7√2

α/sinα = β/sinβ 
7/sin30 = AC/sin (180-105-30)
7/sin30 = AC/sin45
7/1/2 = AC/1/2√2
AC = 7√2