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原题呈现:(2013年南京市中考数学试题第27题)对于两个相似三角形,如果沿周界按对应点顺序环绕的方向相同,那么称这两个三角形互为顺相似;如果沿周界按对应点顺序环绕的方向相反,那么称这两个三角形互为逆相似.例如,如图1(1),△ABC∽△A’B’C’,且沿周界ABCA与A’B’C’A’环绕的方向相同,因此△ABC与△A’B’C’互为顺相似.如图1(2),△ABC∽△A’B’C’,且沿周界ABCA与A’B’C’A’环绕的方向相反,因此△ABC与△A’B’C’互为逆相似.
The original title is: (2013 Nanjing senior high school entrance examination questions 27) For two similar triangles, if the direction along the perimeter according to the order of the corresponding points around the same direction, then called the two triangles mutually cis-similar; if along the perimeter For example, as shown in Figure 1 (1), △ ABC ∽ △ A’B’C ’, and along the perimeter ABCA and A’B’ C ’A’ surround the same direction, so △ ABC and △ A’B’C ’mutually cis similar to Figure 1 (2), △ ABC ∽ △ A’B’C’, and along the perimeter ABCA and A ’B’C’A’ around the opposite direction, so △ ABC and △ A’B’C ’each inverse similar to each other.