A+b+c=180°, sin a= 3/5,dan cos b= 12/13. Tentukan nilai sin c!

a+b+c = 180°
sin a = 3/5, maka cos a = 4/5
cos b = 12/13, maka sin b = 5/13

c = 180° - (a+b)
sin c = sin (180° - (a+b))
sin c = sin 180°.cos (a+b) - cos 180°.sin (a+b)
sin c = 0 - (-1).sin (a+b)
sin c = sin (a+b)
sin c = sin a.cos b + cos a.sin b
sin c = (3/5)(12/13) + (4/5)(5/13)
sin c = 36/65 + 20/65
sin c = 56/65