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Source: 2017 AMC 10B #19, 12B #15

February 16, 2017
ratiogeometryAMCAMC 10AMC 10 B2017 AMC 10B2017 AMC 12B

Problem Statement

Let ABCABC be an equilateral triangle. Extend side AB\overline{AB} beyond BB to a point BB' so that BB=3ABBB' = 3AB. Similarly, extend side BC\overline{BC} beyond CC to a point CC' so that CC=3BCCC' = 3BC, and extend side CA\overline{CA} beyond AA to a point AA' so that AA=3CAAA' = 3CA. What is the ratio of the area of ABC\triangle A'B'C' to the area of ABC\triangle ABC?
<spanclass=latexbold>(A)</span>9:1<spanclass=latexbold>(B)</span>16:1<spanclass=latexbold>(C)</span>25:1<spanclass=latexbold>(D)</span>36:1<spanclass=latexbold>(E)</span>37:1<span class='latex-bold'>(A) </span>9:1\qquad<span class='latex-bold'>(B) </span>16:1\qquad<span class='latex-bold'>(C) </span>25:1\qquad<span class='latex-bold'>(D) </span>36:1\qquad<span class='latex-bold'>(E) </span>37:1