Question

Two identical prisms with triangles as base are joined to form a rectangular prism as shown below.

What is the total surface area of the rectangular prism?

Answer 1

After joining the two prisms we get a rectangular prism which is also called cuboid.

Total surface area $=2(lb+bh+hl)$

$=2(12\times 5+5\times 15+15\times 12)$

$=2(60+75+180)$

$=2\times 315=630c{m}^2$