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Indy100 Staff

Feb 03, 2021

**These two triangles are both made up of four coloured shapes. But in the second triangle there is a missing square**

*Picture: Krauss/Creative Commons*

**This gif confuses things even more**

**So how does the missing square puzzle work? Scroll down to find out**

**The missing square comes about because the slopes on the two triangles are not actually straight**

In fact, the shape of the puzzle is not even technically a triangle - it's a quadrilateral - because the "hypotenuse" (the longest side of the "triangle") is bent.

As *Brightside* explains:

In reality, this is not an optical illusion, but a really interesting task. The areas of the colored pieces are of course equal (32 cells), but even if both figures look like triangles of 13Ã—5, it isnâ€™t so. In fact, they have different areas (S 13Ã—5 = 32.5 cells). So the mystery of the puzzle is that the first figure called a triangle is, in fact, a concave quadrangle.

**This picture of the red and blue triangles helps to highlight the illusion**

**As does this gif from Russian website Novate:**

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