Math Riddle - Can you solve it?

My name is Chris and my passion is to teach math. Learning should never be a struggle which is why I make all my videos as simple and fun as possible. I cover all subjects from basic level math through upper level calculus and statistics. I also make brain teaser, word problems, and Rubik's cube videos for fun.

[alansun]

How were we supposed to know that the blue square covers 1/4 of the red square? There was nothing marked to indicate that besides eyeballing it.

[markderlo]

This solution is elegant but not really simple.
My solution: 2 triangles, created by turning 7x7 square around the ‘centered’ corner are always identical, no matter what would be the angle of the turn; so one triangle will fit exactly into the area of the other triangle, thus creating a small square 3x3, and because that square would have the same area as the shaded shape in question; therefore area = 3x3
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Unfortunatelly, as it happens often, the author did not mark any of the relevant corners or junctions, so it is difficult for me to explain in more details

[kieran]

Great video! I enjoyed figuring this out. Still it was really easy and I haven’t been interested in math since gr 9 (5yrs). So please bring a more challenging one next time😈.

[loiloiloi]

I don't like this problem because of the given length of 5. I was thinking of the solution given here, but I thought there's no way it could be that if the length of 5 is relevant

[Ryuuu]

Ya'll meanies, but he is just explaining the riddle and how to solve it.