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If m∠ABC = 72°, what is m∠DAB?

A) 72°
B) 108°
C) 144°
D) 216°

If m∠ABC = 72°, what is m∠DAB? A) 72° B) 108° C) 144° D) 216°-example-1
User Skoperst
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1 Answer

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∠ABC=∠CDA=72º
∠DAB=∠BCD=x

∠ABC+∠CDA+∠DAB+∠BCD=360º

Therefore:
72º+72º+x+x=360º
144º+2x=360º
2x=360º-144º
2x=216º
x=216º/2
x=108º

So, ∠DAB=∠BCD=x=108º

Answer: ∠DAB=108º (B)
User Enneppi
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