sin 15° + cos 165°=

jawab

sin 15  cos 165 =1/2 ( 2 cos 165 sin 15)
= 1/2 ( sin 180 - sin 150)
= 1/2 (0- sin (180-30))
= 1/2 (0 - sin 30)
= 1/2 (0 - 1/2)
= 1/2 (-1/2)
= 1/4