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MAA AMC
AMC 12/AHSME
1980 AMC 12/AHSME
4
4
Part of
1980 AMC 12/AHSME
Problems
(1)
Angle Measure
Source:
12/30/2005
In the adjoining figure, CDE is an equilateral triangle and ABCD and DEFG are squares. The measure of
∠
G
D
A
\angle GDA
∠
G
D
A
is
(A)
9
0
∘
(B)
10
5
∘
(C)
12
0
∘
(D)
13
5
∘
(E)
15
0
∘
\text{(A)} \ 90^\circ \qquad \text{(B)} \ 105^\circ \qquad \text{(C)} \ 120^\circ \qquad \text{(D)} \ 135^\circ \qquad \text{(E)} \ 150^\circ
(A)
9
0
∘
(B)
10
5
∘
(C)
12
0
∘
(D)
13
5
∘
(E)
15
0
∘
[asy] size(200); 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
A
", A, dir(point--A)); label("
B
B
B
", B, dir(point--B)); label("
C
C
C
", C, dir(point--C)); label("
D
D
D
", D, dir(-15)); label("
E
E
E
", E, dir(point--E)); label("
F
F
F
", F, dir(point--F)); label("
G
G
G
", G, dir(point--G));[/asy]