Question

The base of a prism is a rectangle having sides 5 cm and 12 cm respectively. The height of the prism is 18 cm. It is split vertically along the diagonal of the base into two triangular prisms. What is the total surface area of each of the triangular prism?

• A. $400c{m}^2$
• B. $800c{m}^2$
• C. $1200c{m}^2$
• D. $600c{m}^2$

Answer 1

The correct option is D $600c{m}^2$

Base of the prism has length and breadth as 12 cm and 5 cm respectively.

Diagonal of the base

= $\sqrt{5^2+{12}^2}=13cm$

Total surface area of each triangular prism thus formed

= Lateral surface area + Area of the two triangular faces

= Area of three rectangles + Area of the two triangular faces

$=(12\times 18+5\times 18+13\times 18)+2\times \frac{1}{2}\times 5\times 12$

$=18(12+5+13)+5\times 12$

$=18\times 30+60$

$=540+60$

$=600c{m}^2$