Answer:
О A = 10°
Explanation:
∡ DBC = 180 - 130 = 50°
∡ DBC + ∡ CBD + ∡ BCD = 180°
50° + 70° + ∡BCD = 180°
∡BCD = 180° - (50°+70°)
∡BCD = 180° - 120°
∡BCD = 60°
Then:
∡BCD - ∡DBC = 60° - 50° = 10°
Answer: A
180-130= <D
50=<D
50+70= 120
180-120=<B
60=<B
m<BCD= 70
m<DBC= 60
70-60=10
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