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Byju's Answer
Standard XII
Mathematics
Cos(A+B)Cos(A-B)
Prove that ...
Question
Prove that
1
+
tan
α
⋅
t
a
n
α
2
=
sec
α
Open in App
Solution
LHS
=
1
+
tan
α
⋅
tan
α
2
=
1
+
sin
α
⋅
sin
α
/
2
cos
α
⋅
cos
α
/
2
=
cos
α
⋅
cos
α
/
2
+
sin
α
⋅
sin
α
/
2
cos
α
⋅
cos
α
/
2
=
cos
(
α
−
α
/
2
)
cos
α
⋅
cos
α
/
2
=
cos
α
/
2
cos
α
⋅
cos
α
/
2
=
1
cos
α
=
sec
α
=
RHS.
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If
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