Question

diameter of base of a cone is 10.5cm and its slant height is 10cm. find its curved surface area​

Answer 1

Given:

• Diameter of base of a cone is 10.5cm and its Slant Height is 10cm.

To Find:

• Curved surface area (CSA) of the cone.

Formula Used:

• $\sf{CSA \: of \: cone = \pi \: rl}$

Solution

Let us first find out radius of the cone with the help of radius provided in the Question.

$\\ \longrightarrow\rm{r = \frac{d}{2} } \\ \\ \longrightarrow\rm{r = \dfrac{\cancel{10.5}}{\cancel{2}}} \\ \\ \longrightarrow\rm{r = 5.25cm}$

Here,

• $\tt{\pi = 3.14}$

• $\tt{r = 5.25}$

• $\tt{l = 10}$

Substituting values,

$\\ \longrightarrow\bf{3.14 \times 5.25 \times 10} \\ \\ \longrightarrow\bf{16.485 \times 10} \\ \\ \longrightarrow\bf{164.85} \\ \\ \longrightarrow\bf{165 {cm}^{2} \: (approx) }$

Thus,

$\therefore$ The CSA of cone is 165cm².

Answer 2

Given:

• Diameter of base of cone is 10.5cm and slant height is 10cm.

To find:

• Curved surface area of cone.

Solution:

Diameter=10.5cm

$\sf Radius = \cancel \frac{10.5}{2} \\ \\ \sf Radius = 5.25 \: cm$

The formula of curved surface area of cone is πrl

• π=3.14
• r=5.25cm
• l=10cm

Now put these values in formula!!

πrl

➩3.14×5.25×10

➩16485cm²

$\large \mathcal{ \fcolorbox{orange}{yellow}{ \pink{✯Tʜᴀʟᴀ \: Hᴇʀᴇ}}}$