Solution: Assuming that the side length of a square is R and the side length of a square is also the radius of a circle, then the radius of the circle is also R and the area of the square is R? = 10, and the formula for the area of a circle is πr? , put r? Change it to 10, which means π× 10=3 1.4.

The area of a circle is 3 1.4cm?