Use the net to compute the surface area of the three-dimensional figure.
A) 263 units
B) 319 units
C) 340 units
D) 382 units

Use the net to compute the surface area of the threedimensional figure A 263 units B 319 units C 340 units D 382 units class=

Respuesta :

9514 1404 393

Answer:

  382 square units

Step-by-step explanation:

The central four rectangles down the middle of the net are 9 units wide, and alternate between 8 and 7 units high. Then the area of those four rectangles is ...

  9(8+7+8+7) = 270 . . . square units

The rectangles making up the two left and right "wings" of the net are 8 units high and 7 units wide, so have a total area of ...

  2×(8)(7) = 112 . . . square units

Then the area of the figure computed from the net is ...

  270 +112 = 382 . . . square units

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Additional comment

You can reject the first two answer choices immediately, because they are odd. Each face will have an area that is the product of integers, so will be an integer. There are two faces of each size, so the total area of this figure must be an even number.

You may recognize that the dimensions are 8, 8+1, 8-1. Then the area is roughly that of a cube with dimensions of 8: 6×8² = 384. If you use these values (8, 8+1, 8-1) in the area formula, you find the area is actually 384-2 = 382. That area formula is A = 2(LW +H(L+W)).