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Byju's Answer
Standard X
Mathematics
Trigonometric Identities
If θ = 7 8 ...
Question
If
cot
θ
=
7
8
then find the value of
(
1
+
sin
θ
)
(
1
−
sin
θ
)
(
1
+
cos
θ
)
(
1
−
cos
θ
)
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Solution
(
1
+
s
i
n
θ
)
(
1
−
s
i
n
θ
)
(
1
+
c
o
s
θ
)
(
1
−
c
o
s
θ
)
=
1
−
s
i
n
2
θ
1
−
c
o
s
2
θ
=
c
o
s
2
θ
s
i
n
2
θ
=
c
o
t
2
θ
=
(
7
8
)
2
=
49
64
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Similar questions
Q.
If
cot
θ
=
7
8
, evaluate:
(
1
+
sin
θ
)
(
1
−
sin
θ
)
(
1
+
cos
θ
)
(
1
−
cos
θ
)
Q.
Prove the following trigonometric identities.
(i)
sec
θ
-
1
sec
θ
+
1
+
sec
θ
+
1
sec
θ
-
1
=
2
cosec
θ
(ii)
1
+
sin
θ
1
-
sin
θ
+
1
-
sin
θ
1
+
sin
θ
=
2
sec
θ
(iii)
1
+
cos
θ
1
-
cos
θ
+
1
-
cos
θ
1
+
cos
θ
=
2
cosec
θ
(iv)
sec
θ
-
1
sec
θ
+
1
=
sin
θ
1
+
cos
θ
2
(v)
sin
θ
+
1
-
cos
θ
cos
θ
-
1
+
sin
θ
=
1
+
sin
θ
cos
θ