Geometry

How to solve

A box has three pairs of matching faces: SA = 2(lw + lh + wh).

Steps

  1. Compute the three face areas lw, lh, wh.
  2. Add them.
  3. Double the sum.

Example

A box is 4 by 3 by 2.

  1. lw + lh + wh = 12 + 8 + 6 = 26.
  2. SA = 2 × 26 = 52.

Answer: 52

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