Question

15. The radius of the base of a cone is 21 cm and the height is 20 cm. Find the volume of the cone.​

Answer 1

Answer:

The volume of the cone is 9240 cm³.

Step-by-step-explanation:

We have given that,

• Radius of base of cone ( r ) = 21 cm
• Height of cone ( h ) = 20 cm

We have to find the volume of the cone.

We know that,

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

$\displaystyle{\implies\sf\:Volume\:of\:cone\:=\:\dfrac{1}{3}\:\times\:\dfrac{22}{7}\:\times\:(\:21\:)^2\:\times\:20}$

$\displaystyle{\implies\sf\:Volume\:of\:cone\:=\:\dfrac{1}{3}\:\times\:\dfrac{22}{\cancel{7}}\:\times\:\cancel{21}\:\times\:21\:\times\:20}$

$\displaystyle{\implies\sf\:Volume\:of\:cone\:=\:\dfrac{1}{\cancel{3}}\:\times\:22\:\times\:\cancel{3}\:\times\:21\:\times\:20}$

$\displaystyle{\implies\sf\:Volume\:of\:cone\:=\:22\:\times\:21\:\times\:20}$

$\displaystyle{\implies\sf\:Volume\:of\:cone\:=\:22\:\times\:420}$

$\displaystyle{\implies\sf\:Volume\:of\:cone\:=\:22\:(\:400\:+\:20\:)}$

$\displaystyle{\implies\sf\:Volume\:of\:cone\:=\:22\:\times\:400\:+\:22\:\times\:20}$

$\displaystyle{\implies\sf\:Volume\:of\:cone\:=\:8800\:+\:440}$

$\displaystyle{\implies\:\underline{\boxed{\red{\sf\:Volume\:of\:cone\:=\:9240\:cm^3\:}}}}$

∴ The volume of the cone is 9240 cm³.

Answer 2

GIVEN :-

The radius of the base of a cone is 21 cm and the height is 20 cm

TO FIND :-

Find the volume of the cone = ?

SOLUTION :-

V = 1/3 × r × h

= 1/3 × 22/7 × 21 × 21 × 20

= 440 × 21

= 9240 cm^3