【Haichuan Teahouse】Brain-teasing series; actually has nothing to do with shadows
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The final question in the placement test at a private school
By analyzing the hidden conditions, the area of the shadow can be determined indirectly: lol
How was it calculated? ? ? ?
30 simultaneous equations can be solved, as long as the area is 56 and the conditions shown in the diagram are met. But I took the shortcut and simply set the rectangle to have a length of 8 and a width of 7, thus getting 25 as the result; P
When calculating it, visually it seems to be 56 – (21 + 25 + 16) / 2. The first time I performed the addition, there was no carry, so the result was 30. When you mentioned 25, I added once more and found that there was still no carry. The first answer that comes to mind is still there, so I wrote 30 at the beginning and 25 at the end; P; P; P
This post was last edited by Yang Qing on 2021-7-7 11:07. The method of solving systems of equations doesn’t work, but it’s definitely possible to find the solution by intuition. So take the shortcut. If it’s an exam, it won’t work. There must be a formula; we can’t assume 7 and 8. One can only assume that X and Y
Is your estimate roughly the same as my assumption, which is 7 or 8?
Different paths lead to the same goal, but ultimate tactics take different routes; P: handshake