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Mathematics
Mathematics
Problem
If
A
+
B
+
C
=
180
∘
A + B + C = 180^\circ
A
+
B
+
C
=
18
0
∘
, then prove that
tan
2
θ
2
=
tan
B
2
tan
C
2
\tan^2 \frac{\theta}{2} = \tan \frac{B}{2} \tan \frac{C}{2}
tan
2
2
θ
=
tan
2
B
tan
2
C
, when
cos
θ
(
sin
B
+
sin
C
)
=
sin
A
\cos \theta (\sin B + \sin C) = \sin A
cos
θ
(
sin
B
+
sin
C
)
=
sin
A
.
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