Question

The radius of a solid right circular cone is 65 cm and its height is 72 cm. The total surface area (in cm²) of the cone is (use ∏= 22/7)

• A. 38012 1/7
• B. 43051 3/7
• C. 33094 2/7
• D. 43084 5/7

Answer 1

Answer:

C. 33094 2/7

For a cone, total surface area = curved surface area + base area:

$\text{TSA} = \pi r (r + l)$

First find the slant height (l):

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

$l = \sqrt{65^2 + 72^2} = \sqrt{4225 + 5184} = \sqrt{9409} = 97 \text{ cm}$

Now,

$\text{TSA} = \frac{22}{7} \times 65 \times (65 + 97)$
$= \frac{22}{7} \times 65 \times 162$
$= \frac{22}{7} \times 10530$
$= 22 \times 1504.2857 = 33100$

Total surface area = 33,100 cm²