What is the total surface area (correct to two places of decimals) of a right circular cone with height of 8 m and base radius 4 m? (Use $$\pi = \frac {22}{7} and \sqrt 5 = 2.34).$$​)

Correct option is D

Given:

Height (h) = 8 m

Base radius (r) = 4 m

π =$$\frac{22}{7}$$​​

​$$\sqrt{5}$$​ = 2.34

We need Total Surface Area (TSA) of cone

Formula Used:

Slant height:

l $$= \sqrt{r^2 + h^2}$$​

Total Surface Area of cone:

TSA =$$\pi r (l + r)$$​

Solution:

Compute slant height:

l =$$\sqrt{4^2 + 8^2} = \sqrt{16 + 64} = \sqrt{80} = \sqrt{16 \times 5} = 4 \sqrt{5}$$​

l $$= 4 \times 2.34 = 9.36 \ \text{m}$$​

TSA =$$\frac{22}{7} \times 4 \times (9.36 + 4)$$​

​$$= \frac{88}{7} \times 13.36 \approx 167.95 \ \text{m}^2$$​