Question

The curved surface area of a cone with radius 3 cm and height 4 cm is...​

Answer 1

Given :

• Radius of Cone = 3cm
• Height of Cone = 4cm

To Find :

• C.S.A of Cone

Solution :

$\longmapsto\tt{Radius=3cm}$

$\longmapsto\tt{Height=4cm}$

Firstly we will find the Slant Height :

$\longmapsto\tt\bold{{l}^{2}=\sqrt{{h}^{2}+{r}^{2}}}$

$\longmapsto\tt{{l}^{2}=\sqrt{{(4)}^{2}+{(3)}^{2}}}$

$\longmapsto\tt{{l}^{2}=\sqrt{{16+9}}}$

$\longmapsto\tt{{l}^{2}=\sqrt{25}}$

$\longmapsto\tt{l=5cm}$

Slant height (l) of the cone is 5cm..

_______________________

Using Formula :

$\longmapsto\tt\boxed{C.S.A\:of\:Cone=\pi{rl}}$

Putting Values :

$\longmapsto\tt{\dfrac{22}{7}\times{3}\times{5}}$

$\longmapsto\tt{\cancel\dfrac{330}{7}}$

$\longmapsto\tt\bold{47.1{cm}^{2}}$

So , The C.S.A of Cone is 47.1 cm²...