Question

What is the total surface area of a cone with slant height $9$ m and radius of base $6$ m?

• A. $28286$ m${}^2$
• B. $2828.6$ m${}^2$
• C. $28.286$ m${}^2$
• D. $282.86$ m${}^2$

Answer 1

Answer: (D)

$282.86$ m${}^2$

Slant height l$=9m$
Radius of the base r $=6m$
Curved surface area = $\pi rl=\frac{22}{7}\times 6m\times 9m\approx 169.71m^2$
Aera of the base = $\pi r^2=\frac{22}{7}\times 6m\times 6m=113.14m^2$
Total surface area = Curved surface area + Base area
$=(169.71+113.14)m$${}^2$ $=282.85$ m${}^2$