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Mathematics
Mathematics
Problem
Show that
2
sin
2
β
+
4
cos
(
α
+
β
)
sin
α
sin
β
+
cos
2
(
α
+
β
)
=
cos
2
α
2 \sin^2 \beta + 4 \cos(\alpha + \beta) \sin \alpha \sin \beta + \cos 2(\alpha + \beta) = \cos 2\alpha
2
sin
2
β
+
4
cos
(
α
+
β
)
sin
α
sin
β
+
cos
2
(
α
+
β
)
=
cos
2
α
.
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