Answer :
Answer:
1 is the correct answer u can also check it by solving once
Step-by-step explanation:
Given that
B
+
C
=
120
∘
B
2
+
C
2
=
60
∘
B
2
−
30
∘
=
30
∘
−
C
2
N
o
w
,
b
c
+
a
+
c
a
+
b
−
sin
B
sin
A
+
sin
C
+
sin
C
sin
A
+
sin
B
=
sin
B
2
sin
(
C
+
A
2
)
cos
(
A
−
C
2
)
+
sin
C
2
sin
(
A
+
B
2
)
cos
(
A
−
B
2
)
=
sin
B
2
cos
(
A
−
C
2
)
+
sin
C
2
cos
(
A
−
B
2
)
=
sin
B
2
cos
(
30
∘
−
C
2
)
+
sin
(
C
2
)
cos
(
30
∘
−
B
2
)
=
sin
B
2
cos
(
B
2
−
30
∘
)
+
sin
C
2
cos
(
30
∘
−
B
2
)
=
1
cos
(
30
∘
−
B
2
)
2
sin
30
∘
cos
(
B
−
C
4
)
=
2
×
1
2
×
1
cos
(
30
∘
−
B
2
)
×
cos
(
B
2
−
30
∘
)
=
1