This question need you to think outside the box | Math puzzle

This question is also from a Japanese middle school entry test.
Please have a try~
If you can think outside the box, no trig or no coordinate system is needed.
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[@brock2k1]

This is harder than anything in the math section of the GRE (for college grads). If this really is from a Japanese middle school test, it's for a math olympiad or something similar, not an entrance test.

[@doubledonut9313]

This is the test paper.
www.logix-shuppan.com/explanation/2019nada1.pdf
it is considered to be the hardest maths entry test in Japan.
honestly, I also think it is a tricky question, but it should be doable by a high school kid if they really try

[@YHHSU-k7e]

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