evaluate the volume of the cone.Use ñ=3.14

The circumference of the base is 40 cm, and this equals 2*pi*r. The radius, r, is found as follows:
40 cm
r = ------------ = 6.369 cm. The area of the base, A = pi*r^2, = 3.14*40.570
2(3.14)
The volume here is V = (1/3)(area of base)*(height)
= (1/3)(127.45)(9) cm^3 = 382.36 cm^3 (answer)