The volume of a cone is 1570 cm3 and its height is 15 cm.

(a) 10 cm
Let r cm be the radius of the cone.
Volume = 1570  cm3

Then $\frac{1}{3} \times 3.14 \times r^{2} \times 15=1570$
$\Rightarrow r^{2}=\frac{1570}{3.14 \times 5}=100$

$\Rightarrow r=10 \mathrm{~cm}$