Calculate the surpace area of the rectangular solid shown with a height of 12 length of 13 and width of 21?

Question

A. 681
B. 1092
C. 1362
D. 3276

Answer 1

Each of the 6 surfaces is a rectangle.
Opposite sides have the same dimensions.
So there are 3 different sets of 2 identical sides.
Total surface area is the sum of these.
2(12 x 13 + 12 x 21 + 13 x 21) =
2(156 + 252 + 273) =
2(681) =
1362 =
C

Answer 2

surface area = 2 [ 13(21) + 12(21) + 12(13) ] = 1362
c. 1362