Question

The base of the vertical pillar with the uniform cross-section is a trapezium whose parallel sides are of length 10 cm and 20 cm while the other two sides are of equal length. The perpendicular distance between the parallel sides of the trapezium is 12 cm. If the height of the pillar is 20 cm, find the total area, in sq cm, of all six surfaces of the pillar is

• A. 1300
• B. 1340
• C. 1480
• D. 1520

Answer 1

The correct option is C

1480

The diagram given below represents the cross-section of the pillar.



Total surface area of all the six surfaces = Area of 4 walls + Area of top and bottom
$\Rightarrow$(Perimeter of the trapezium x Height of the pillar) + 2 x Area of the trapezium
$\Rightarrow$(10 + 13 + 13 + 20) x 20 + 2 x $\frac{1}{2}$ x (10 + 20) x 12 $\Rightarrow$1120 + 360 $\Rightarrow$1480