BTGmoderatorLU wrote:Source: Economist GMAT
What is the area of the shaded region, formed by the intersection of an equilateral triangle with area √3, and an inscribed circle, as shown above?
$$A.\ \sqrt{3}-3\pi$$
$$B.\ \sqrt{3}-\frac{4}{3}\pi$$
$$C.\ \frac{3\sqrt{3}}{4}$$
$$D.\ \sqrt{3}-\frac{\pi}{3}$$
$$E.\ 3\sqrt{3}-\pi$$
The OA is
D.
You may solve this by PoE.
Area of shaded region = Area of the equilateral triangle – Area of the circle
= √3 – nπ; where n is any positive number
Since Area of the shaded region is a positive quantity, we have √3 – nπ > 0.
Now let's look at the options.
A. √3 – 3π: This is a negative number; eliminated!
B. √3 – (4/3)π: This is also a negative number; eliminated!
C. (3√3) / 4; We see that π is missing in the expression; even if we consider that π = 22/7 is plugged-in, the expression must have 7√3 (π = 22/7). Since none of the conditions is met, we can eliminate this too.
D. √3 – π/3: A contender for the correct answer
E. 3√3 – π: Since the value of the shaded area should be significantly less than √3, and we find that (3√3 – π) > √3, we can eliminate this too.
The correct answer:
D
Hope this helps!
-Jay
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Last edited by Jay@ManhattanReview on Thu Sep 27, 2018 9:49 pm, edited 1 time in total.