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Contests
National and Regional Contests
USA Contests
MAA AMC
AMC 12/AHSME
1962 AMC 12/AHSME
18
18
Part of
1962 AMC 12/AHSME
Problems
(1)
Regular Dodecagon
Source:
3/3/2010
A regular dodecagon (
12
12
12
sides) is inscribed in a circle with radius
r
r
r
inches. The area of the dodecagon, in square inches, is:
<
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(
A
)
<
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3
r
2
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(
B
)
<
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2
r
2
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(
C
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3
r
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3
4
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(
D
)
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r
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3
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E
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r
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3
<span class='latex-bold'>(A)</span>\ 3r^2 \qquad <span class='latex-bold'>(B)</span>\ 2r^2 \qquad <span class='latex-bold'>(C)</span>\ \frac{3r^2 \sqrt{3}}{4} \qquad <span class='latex-bold'>(D)</span>\ r^2 \sqrt{3} \qquad <span class='latex-bold'>(E)</span>\ 3r^2 \sqrt{3}
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(
A
)
<
/
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>
3
r
2
<
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>
(
B
)
<
/
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>
2
r
2
<
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(
C
)
<
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>
4
3
r
2
3
<
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a
ss
=
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l
a
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x
−
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>
(
D
)
<
/
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>
r
2
3
<
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>
(
E
)
<
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3
r
2
3
geometry
trigonometry