Question

A concrete pillar has a radius of 3.5 cm and a length of 15 cm. The total surface area of the pillar is ______.

• A. $417{\text{cm}}^2$
• B. $410{\text{cm}}^2$
• C. $407{\text{cm}}^2$
• D. $414{\text{cm}}^2$

Answer 1

The correct option is C

$407{\text{cm}}^2$

Radius = 3.5 cm

Height of the pillar = Length of the pillar = 15 cm

Total Surface Area $=\text{Curved surface area}+2\times \text{Base area}$

$=2\pi rh+2\pi r^2$

$=2\pi r(h+r)$

$=2\times \frac{22}{7}\times 3.5(15+3.5)$

$=22\times 18.5$

$=407{\text{cm}}^2$