ANSWER TO THE brain teaser

The trick to this visual puzzle is the simple assumption that both figure 1 and figure 2 are 13 (wide) by 5 (high) triangles.

They are both 13 by 5, but they are not both triangles. A close look will reveal that the green triangles and red triangles have sllightly different slopes.

The clues are all there: Slope is described as rise/run or 3/8 (0.378) for the red triangle and 2/5 (0.40) for the green triangle. The difference is slight but noticeable. Take another look at the triangles to see how the hypotenuse in fig.1 “dips in” but “bulges out” in fig. 2.

The difference in area happens to account for one full square unit.

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