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MackyCee
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MackyCee
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MackyCee
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Musta been the time of night - but you are definitely 100% correct (as is MGMAT), it doesn't have to be isosceles at all, I must have had my head n the clouds with another concept :S

I need a holiday! haha
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Hey,

I also did the mistake but I think MGMAT is right. But this is typical DS question which tricks you with mixed information.

(1) From first you only see one rt angle triangle on the left hand side is 30-60-90 but still do not know anything on the right hand side rt angle triangle

(2) From this statement you know only one side of the base. The point D is not the midpoint. Hence you do know know the lenght of whole base.

(1) & (2) You know the lenght of whole base BD + DC and you have the height given.

Hence C is the right answer.
Please correct me if i am wrong :-)
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A realiy tough question. I too made the same mistake... :(
kudos to MGMAT.
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C is the answer, that was tough! whew! :shock:
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C is the answer. It was easy guys, pretty straight forward.

When nothing is given about the figure, one should take only the info that is present in the question.
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I don't see how C can be right. If I follow your reasoning, I come to E. (I chose B)

Can anyone explain the calculations?
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unceldolan
I don't see how C can be right. If I follow your reasoning, I come to E. (I chose B)

Can anyone explain the calculations?


If AD is 6 and ADC is a right angle, what is the area of triangular region ABC?

Given: \(AD=6\). Question: \(area_{ABC}=\frac{1}{2}*AD*BC=\frac{1}{2}*6*(BD+DC)=3(BD+DC)=?\)

(1) Angle ABD = 60 --> triangle ABD is 30-60-90 triangle, so the sides are in ratio \(1:\sqrt{3}:2\) --> as AD=6 (larger leg opposite 60 degrees angle) then \(BD=\frac{6}{\sqrt{3}}\) (smallest leg opposite 30 degrees angle). But we still don't know DC. Not sufficient.

(2) AC=12, we can find DC. But we still don't know BD. Not sufficient.

(1)+(2) We know both BD and DC, hence we can find area. Sufficient.

Answer: C.

OPEN DISCUSSION OF THIS QUESTION IS HERE: if-ad-is-6-and-adc-is-a-right-angle-what-is-the-area-of-101200.html
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