In an isosceles triongle if the vertex angle is thric the sum of the based angles then the measure of the vertex angle is
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Answer:
Ans:120 Degree
Step-by-step explanation:
The correct option is B
120
∘
(b),
I
n
Δ
A
B
C
,
∠
A
=
2
(
∠
B
+
∠
C
)
=
2
∠
B
+
2
∠
C
A
d
d
i
n
g
2
∠
A
to both sides,
∠
A
+
2
∠
A
=
2
∠
A
+
2
∠
B
+
2
∠
C
⇒
3
∠
A
=
2
(
∠
A
+
∠
B
+
∠
C
)
⇒
3
∠
A
=
2
×
180
∘
(
∵
∠
A
+
∠
B
+
C
=
180
∘
)
⇒
3
∠
A
=
360
∘
⇒
∠
A
=
360
∘
3
=
120
∘
∴
∠
A
=
120
∘
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