Difficulty: Medium
Correct Answer: 236 cm2
Explanation:
Introduction / Context:
Same setup as a classic identity problem: with l + b + h and the space diagonal known, compute the pairwise products and hence the total surface area.
Given Data / Assumptions:
Concept / Approach:
Use (l + b + h)^2 = d^2 + 2(lb + bh + hl). Rearranging gives the sum of pairwise products directly.
Step-by-Step Solution:
(l + b + h)^2 − d^2 = 361 − 125 = 2362(lb + bh + hl) = 236 ⇒ S = 236 cm2
Verification / Alternative check:
Dimensions need not be individually determined; identity-based computation is sufficient.
Why Other Options Are Wrong:
361 and 125 are intermediate squares; “None” is unnecessary once identity is applied.
Common Pitfalls:
Forgetting to take 2 into account or mis-squaring 19.
Final Answer:
236 cm2
Discussion & Comments