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Problem
Problem
Find
cos
(
α
+
β
)
\cos(\alpha + \beta)
cos
(
α
+
β
)
, if
tan
α
2
\tan \frac{\alpha}{2}
tan
2
α
and
tan
β
2
\tan \frac{\beta}{2}
tan
2
β
are roots of the equations
8
x
2
−
26
x
+
15
=
0
8x^2 - 26x + 15 = 0
8
x
2
−
26
x
+
15
=
0
.
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