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When applied to transformational geometry, the determinant of a 2 × 2 matrix signifies the ratio of the area of the transformed shape to the original and its sign (plus or minus) denotes whether the image is direct (the same way round) or indirect (a mirror image).
For example
White represents the snow on Monte Titano and the clouds above. Blue stands for the sky. Effective date: 6 April 1862.
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