Question

In the figure, △ABC and △BOD are two congruent triangles. Then the measure of ∠B



70°

80°

30°

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Answer 1

Answer:

geometry instruments so its difficult

Answer 2

Answer:

∠ABF + ∠ABC = 180° (linear pair)

⇒ x + ∠ABC = 180° 

⇒ ∠ABC = 180° - x

 

∠ACG + ∠ACB = 180° (linear pair)

⇒ y + ∠ACB = 180° 

⇒ ∠ACB = 180° - y

 

In ΔABC, by angle sum property

∠ABC + ∠ACB + ∠BAC = 180° 

⇒ (180° - x) + (180° - y) + ∠BAC = 180° 

⇒ ∠BAC - x - y + 180° = 0

⇒ ∠BAC = x + y - 180° 

 

Now, ∠EAD = ∠BAC (vertically opposite angles)

⇒ z = x + y - 180°