Question

9. Perhatikan gambar!
Besar ∠BAC adalah ….
(UN SMP 2011)
a. 24°
b. 48°
c. 72°
d. 98°

Answer 1

UN MATEMATIKA 2011
Materi Sudut 
Kelas VII

∠BAC + ∠ ABC = ∠DCB
∠BAC + 36° = 108°
∠BAC = 108° - 36°
∠BAC = 72° (C)

atau

∠DCB + ∠ACB = 180° [Garis Lurus]
108° + ∠ACB = 180°
∠ACB = 72°

∠ACB + ∠BAC + ∠ABC = 180° [Segitiga]
72° + ∠BAC + 36° = 180°
∠BAC = 180° - 108°
∠BAC = 72° (C)

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