Tolong bantu jawab no 2 sampai no 4

27)
x = (180° - 120°) + (180° - 130°)
= 60° + 50°
= 110°

atau

x = 360° - (120° + 130°)
= 360° - 250°
= 110°

28)

SEGITIGA ABC
K = 64 cm
AB = (2x-5)
BC = (x+13)
AC = (3x-16)

a)
K = AB + BC + AC
64 = 2x - 5 + x + 13 + 3x - 16
64 = 6x - 8
6x = 64 + 8
6x = 72
x = 72/6
x = 12
b)
panjang AB = 2x - 5
= 2×12 - 5
= 24 - 5
= 19 cm
panjang BC = x + 13
= 12 + 13
= 25 cm
panjang AC = 3x - 16
= 3×12 - 16
= 36 - 16
= 20 cm
29)
BE = BC = CD = DE = AF = 15 cm
CE = 24 cm
FE = 30 cm
tinggi trapesium (t) = 1/2 × CE
= 1/2 × 24
= 12 cm
BD = 2 × [akar (BE^2 - (1/2×CE)^2)]
= 2 × [akar (15^2 - (1/2×24)^2)]
= 2 × [akar (15^2 - 12^2)]
= 2 × [akar (225 - 144)]
= 2 × [akar 81]
= 2 × 9
= 18 cm
AB = FE - BD
= 30 - 18
= 12 cm
L = L trapesium + L belah ketupat
= [1/2×(FE+AB)×t] + [1/2×BD×CE]
= [1/2×(30+12)×12] + [1/2×18×24]
= [1/2×42×12] + [1/2×18×24]
= 252 + 216
= 468 cm^2