1997 AHSME Problems/Problem 2

Problem

The adjacent sides of the decagon shown meet at right angles. What is its perimeter?

$[asy] defaultpen(linewidth(.8pt)); dotfactor=4; dot(origin);dot((12,0));dot((12,1));dot((9,1));dot((9,7));dot((7,7));dot((7,10));dot((3,10));dot((3,8));dot((0,8)); draw(origin--(12,0)--(12,1)--(9,1)--(9,7)--(7,7)--(7,10)--(3,10)--(3,8)--(0,8)--cycle); label("$8$",midpoint(origin--(0,8)),W); label("$2$",midpoint((3,8)--(3,10)),W); label("$12$",midpoint(origin--(12,0)),S);[/asy]$

$\mathrm{(A)\ } 22 \qquad \mathrm{(B) \ }32 \qquad \mathrm{(C) \ } 34 \qquad \mathrm{(D) \ } 44 \qquad \mathrm{(E) \ }50$

Solution

The three unlabelled vertical sides have the same sum as the two labelled vertical sides, which is $10$ .

The four unlabelled horizontal sides have the same sum as the one large horizontal side, which is $12$ .

Thus, the perimeter is $2(12+10) = 44$ , which is option $\boxed{D}$ .

1997 AHSME (Problems • Answer Key • Resources)
Preceded by Problem 1	Followed by Problem 3
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1997 AHSME Problems/Problem 2

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