Difference between revisions of "1980 AHSME Problems/Problem 4"

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label("$F$", F, dir(point--F));
 
label("$F$", F, dir(point--F));
 
label("$G$", G, dir(point--G));</asy>
 
label("$G$", G, dir(point--G));</asy>
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== Solution ==
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<math> m\angle GDA=360^\circ-90^\circ-60^\circ-90^\circ=120^\circ\Rightarrow\boxed{C} </math>
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== See also ==
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{{AHSME box|year=1980|num-b=3|num-a=5}}
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{{MAA Notice}}

Latest revision as of 11:47, 5 July 2013

Problem

In the adjoining figure, CDE is an equilateral triangle and ABCD and DEFG are squares. The measure of $\angle GDA$ is

$\text{(A)} \ 90^\circ \qquad \text{(B)} \ 105^\circ \qquad \text{(C)} \ 120^\circ \qquad \text{(D)} \ 135^\circ \qquad \text{(E)} \ 150^\circ$

[asy] defaultpen(linewidth(0.7)+fontsize(10)); pair D=origin, C=D+dir(240), E=D+dir(300), F=E+dir(30), G=D+dir(30), A=D+dir(150), B=C+dir(150); draw(E--D--G--F--E--C--D--A--B--C); pair point=(0,0.5); label("$A$", A, dir(point--A)); label("$B$", B, dir(point--B)); label("$C$", C, dir(point--C)); label("$D$", D, dir(-15)); label("$E$", E, dir(point--E)); label("$F$", F, dir(point--F)); label("$G$", G, dir(point--G));[/asy]

Solution

$m\angle GDA=360^\circ-90^\circ-60^\circ-90^\circ=120^\circ\Rightarrow\boxed{C}$

See also

1980 AHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 3
Followed by
Problem 5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
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