Question

2
7. If the area of base of the cone is 420 cm
and its height is 15 cm, then find its volume.​

Answer 1

Step-by-step explanation:

Given:-

• The area of the base of the cone = 420cm²

• Height of the cone = 15cm

To Find:-

• The Volume of the cone.

Solution:-

The area of the base of the cone = 420cm²

$\sf \implies\pi {r}^{2} = 420$

$\sf \implies\dfrac{22}{7}\times {r}^{2} = 420$

$\sf \implies {r}^{2} = 420 \times \dfrac{7}{22}$

$\sf \implies {r}^{2} = 133.63$

$\sf \implies r = \sqrt{133.63}$

$\sf \implies r = 11.56cm$

Radius of the cone = 11.56cm

Height of the cone = 15cm

$\sf Volume \: of \: the\: cone = \dfrac{1}{3} \pi r^2 h$

$\sf = \dfrac{1}{3} \times \dfrac{22}{7} \times (11.56)^{2} \times 15$

$\sf = \dfrac{22}{7} \times 133.63 \times 5$

$\sf = 2099.95$

$\underline{\boxed{\sf \therefore Volume \: of \: the \: cone \approx 2099.95cm^3}}$

Answer 2

Answer:

Area of base = 420 cm²

=> πr² = 420 cm²

Height (h) = 15 cm

Volume of cone = πr²h/3 = 420×15/3 = 2100 cm³