Question

the radius of a circle is doubled. a . how does the circumference change? b. How does the area change?

Answer 1

Let's say the original radius was "r", so the circumference is 2πr and the area is πr².

Now when you double the radius, the you get a new circle with radius 2r, circumference 2π(2r) = 4πr, and area π(2r)² = 4πr².