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Mathematics
Mathematics
Problem
Prove that
sin
x
cos
3
x
+
sin
3
x
cos
9
x
+
sin
9
x
cos
27
x
=
1
2
(
tan
27
x
−
tan
x
)
\frac{\sin x}{\cos 3x} + \frac{\sin 3x}{\cos 9x} + \frac{\sin 9x}{\cos 27x} = \frac{1}{2} (\tan 27x - \tan x)
cos
3
x
sin
x
+
cos
9
x
sin
3
x
+
cos
27
x
sin
9
x
=
2
1
(
tan
27
x
−
tan
x
)
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