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Mathematics
Mathematics
Problem
If
2
cos
A
=
x
+
1
x
2 \cos A = x + \frac{1}{x}
2
cos
A
=
x
+
x
1
,
2
cos
β
=
y
+
1
y
2 \cos \beta = y + \frac{1}{y}
2
cos
β
=
y
+
y
1
then show that
2
cos
(
A
−
B
)
=
x
y
+
y
x
2 \cos(A - B) = \frac{x}{y} + \frac{y}{x}
2
cos
(
A
−
B
)
=
y
x
+
x
y
.
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