Question

calculate the area of the side surface of the roll.

Answer 1

The diamerer of the circular base is 18 cm.

Since the diameter is 2 radii, it follows that the radius r is given by:

$r=\frac{18}{2}=9$

Therefore, the lateral surface area is given by:

$2\pi\times9\times7\approx395.84\text{ cm}^2$

Therefore, the required area is:

395.84 cm²