The radius of the circle is doubled and its circumference is doubled______ It expanded to its original size______ ．

The radius of the circle is doubled and its circumference is doubled______ It expanded to its original size______ ．

Suppose the radius of the original circle is r, then the diameter is 2R, the circumference of the circle is 2 π R, and the area of the circle is π R2. After the radius is doubled, the radius of the circle is 2R, the diameter of the circle is 4R, the circumference of the circle is 4 π R, the area of the circle is (2R) 2 π = 4 π R2, and the circumference is expanded to the original 4 π R △ 2 π r = 2, and the area is expanded to