Question.
The height of a cone is $15 \mathrm{~cm}$. If its volume is $1570 \mathrm{~cm}^{3}$, find the diameter of its base. [Use $\left.\pi=3.14\right]$
The height of a cone is $15 \mathrm{~cm}$. If its volume is $1570 \mathrm{~cm}^{3}$, find the diameter of its base. [Use $\left.\pi=3.14\right]$
Solution:
Height (h) of cone = 15 cm
Let the radius of the cone be r.
Volume of cone $=1570 \mathrm{~cm}^{3}$
$\frac{1}{3} \pi r^{2} h=1570 \mathrm{~cm}^{3}$
$\Rightarrow\left(\frac{1}{3} \times 3.14 \times r^{2} \times 15\right) \mathrm{cm}=1570 \mathrm{~cm}^{3}$
$\Rightarrow r^{2}=100 \mathrm{~cm}^{2}$
⇒ r = 10 cm
Therefore, the diameter of the base of cone is 10×2=20 cm
Height (h) of cone = 15 cm
Let the radius of the cone be r.
Volume of cone $=1570 \mathrm{~cm}^{3}$
$\frac{1}{3} \pi r^{2} h=1570 \mathrm{~cm}^{3}$
$\Rightarrow\left(\frac{1}{3} \times 3.14 \times r^{2} \times 15\right) \mathrm{cm}=1570 \mathrm{~cm}^{3}$
$\Rightarrow r^{2}=100 \mathrm{~cm}^{2}$
⇒ r = 10 cm
Therefore, the diameter of the base of cone is 10×2=20 cm
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