Question

In the diagram all the angles shown are right angles. The length of AB=4 and BC=5 as indicated in the diagram. What is the perimeter of the entire figure?

Answer 1

The perimeter of the entire figure would be 18.

Answer 2

Answer: choice C, 18

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Explanation:

We don't know how long each little horizontal piece is, but we do know that the smaller horizontal pieces combine to fully span 5 units across. The top and bottom sides effectively are both 5 units long. Think of a rectangle. Similarly, the same happens with the vertical pieces as well. They combine to get 4.

We have a figure with a perimeter similar to a rectangle that is 4 by 5, the perimeter being 4+5+4+5 = 9+9 = 18

Alternatively, you can use the formula

P = 2*L + 2*W or P = 2*(L+W)

Plug in L = 5 and W = 4 as the length and width to get P = 18 for the perimeter