Question

If a radius of a circle is doubled area is multiplied by

Answer 1

If the radius of a circle is doubled, the area of the circle will be quadrupled and the circumference will also be doubled. This makes sense because the area of a circle is directly proportional to the square of the radius of the circle (if the radius of a circle is increased x times, its area will be increased to x^2 times the original area), whereas the circumference is proportional to the size of the radius (if the radius of a circle is increased x times, its circumference will increase x times).