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Byju's Answer
Standard XII
Mathematics
Trigonometric Ratios of Compound Angles
If sinα+βsi...
Question
If
sin
(
α
+
β
)
sin
(
α
−
β
)
=
a
+
b
a
−
b
then prove that
a
tan
β
=
b
tan
α
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Solution
We have,
s
i
n
(
α
+
β
)
s
i
n
(
α
−
β
)
=
a
+
b
a
−
b
Applying componendo and dividendo
sin
(
α
+
β
)
+
sin
(
α
−
β
)
sin
(
α
+
β
)
−
sin
(
α
−
β
)
=
a
+
b
+
a
−
b
a
+
b
−
(
a
−
b
)
sin
C
+
sin
D
=
2
sin
(
C
+
D
2
)
.
cos
(
C
−
D
2
)
sin
C
−
sin
D
=
2
cos
(
C
+
D
2
)
.
sin
(
C
−
D
2
)
∴
2
sin
α
.
cos
β
2
cos
α
.
sin
β
=
a
b
tan
α
tan
β
=
a
b
∴
a
tan
β
=
b
tan
α
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0
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