tolong dibantu... terimakasihh

3.
BC/sin 30 = AB/sin C
12 / 1/2 = 12 akar 3 / sin C
sin C = 1/2 akar 3
C = 60°

sudut B = 180 - 60 - 30 = 90°

AC^2 = AB^2 + BC^2
AC^2 = (12 akar3)^2 + 12^2
AC^2 = 432 + 144 = 576
AC = 24 cm

4.
tan 60 = akar 3
CD/4 = akar 3
CD = 4 akar 3 cm

BD cos60 = 4
BD . 1/2 = 4
BD = 8 cm

tan 30 = 1/3 akar 3
4 akar 3 / AC = 1/3 akar 3
AC = 12 cm

AB = 12 - 4 = 8 cm