Question

The height of a cone is 4 cm and its base radius is 3 cm. The total surface area of the cone is:

• A. 68 $c{m}^2$
• B. 75.42 $c{m}^2$
• C. 89.5 $c{m}^2$
• D. 93.23 $c{m}^2$

Answer 1

The correct option is B

75.42 $c{m}^2$

Here, h = 4 cm and r = 3 cm.

We know, slant height is given by,

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

$⟹l^2=h^2+r^2$

$⟹l^2=4^2+3^2$

$⟹l^2=16+9$

$⟹l=5cm$

$\text{So, total surface area}=\pi rl+\pi r^2=\pi r(l+r)=\frac{22}{7}\times 3(5+3)=75.42{\text{cm}}^2$