Please, help to solve the question!!!

Question

Can anybody help to solve the problem solving question???

nick_sun · Answer

I think it is (B).

ABC is equilateral => angle A = angle B = angle C = 60
ACD is also equilateral => angle A = angle B = angle C = 60
=> angle A in ABD = 120
AB = AD => ABD is isosceles => angle B = angle D = 180 - 120 / 2 = 30 :-D

Tuneman · Answer

Yes you are right its 30. I HATED this question I had no idea how to do it. I am not sure how to prove that the arc of BC is equal to the radius, but it is, and thus BAC is 60 and the answer is B 30.

vshaunak@gmail.com · Answer

IMO, the answer is 30 degree.

AB = BC = AC => ABC is an equilateral triangle=> angle BAC is 60 degree
that means angle DAC = 60 degree
As per the rule - angle made by the arc on center is twice the angle made by the same arc on the circumference. Here the angle DAC made by the arc DC on the center is 60 degree. So the DBC = 30. 
As angle ABC = 60 degree, the angle ABD = x = 30 degree

amd08 · Answer

from given info and figure it is clear that AB=BC=AC=AD=DC. Here basically BD connects two opposite vertices of 2 equi. triangles with common base AC. Hence, it should be dividing the the angles B and D into half. i.e. 60/2 = 30

Vlad77 · Answer

Thanks a lot

!!!!

Please, help to solve the question!!!

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