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Puzzle:
"Suppose I inscribe a circle within a square so that the circle just touches the four sides of the square. Suppose there is exactly enough room to fit a rectangle of dimensions 5 × 10 into one corner of the square so that the rectangle just touches the circle. See Figure 1.1. What is the side length of the square?"
- it is quite simple since we have already known that the radius of the circle must be half of the square.
- set the radius to x,
- solve it
