2006 AMC 12B Problem 16

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Concepts:regular polygondistance formulaarea

Difficulty rating: 1740

16.

Regular hexagon ABCDEFABCDEF has vertices AA and CC at (0,0)(0, 0) and (7,1),(7, 1), respectively. What is its area?

20320\sqrt{3}

22322\sqrt{3}

25325\sqrt{3}

27327\sqrt{3}

5050

Solution:

The distance is AC=72+12=50.AC = \sqrt{7^2 + 1^2} = \sqrt{50}. In a regular hexagon with side s,s, the distance between vertices two apart is s3,s\sqrt3, so s23=50,s^2 \cdot 3 = 50, giving s2=503.s^2 = \dfrac{50}{3}.

The hexagon's area is 332s2=332503=253.\frac{3\sqrt3}{2}s^2 = \frac{3\sqrt3}{2} \cdot \frac{50}{3} = 25\sqrt3.

Thus, the correct answer is C.

Problem 16 in Other Years