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Mathematics
Mathematics
Problem
In triangle
A
B
C
ABC
A
B
C
,
∠
A
=
∠
C
\angle A = \angle C
∠
A
=
∠
C
. The exterior angle at vertex
B
B
B
measures
140
∘
140^\circ
14
0
∘
. What is
∠
A
\angle A
∠
A
? a)
40
∘
40^{\circ}
4
0
∘
b)
70
∘
70^{\circ}
7
0
∘
c)
20
∘
20^{\circ}
2
0
∘
d)
60
∘
60^{\circ}
6
0
∘
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