Sixth-grade primary school students solve problems in the ninth week of mathematics newspaper, the answer to the third small question! ! ! ! Emergency emergency emergency emergency emergency emergency! ! As can be seen from the figure, the width of the rectangle is equal to the radius of the circle, and the area of the rectangle is equal to the area of the circle.

Let the radius of a circle be r, the area of a rectangle be 10*r, and the area of a circle be the square of s = π * r.

Then the square solution of 10*r=π*r is 10 = π *r, then r = 10/π(π- one tenth).