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Byju's Answer
Standard X
Mathematics
Variation of Trigonometric Ratios from 0 to 90 Degrees
Question 5If ...
Question
Question 5
If
s
e
c
4
A
=
c
o
s
e
c
(
A
−
20
∘
)
, where 4A is an acute angle, find the value of A.
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Solution
According to the question,
s
e
c
4
A
=
c
o
s
e
c
(
A
−
20
∘
)
Since
c
o
s
e
c
(
90
−
θ
)
=
s
e
c
θ
⇒
c
o
s
e
c
(
90
∘
−
4
A
)
=
c
o
s
e
c
(
A
−
20
∘
)
Equating angles,
90
∘
−
4
A
=
A
−
20
∘
⇒
110
∘
=
5
A
⇒
A
=
22
∘
,
(
a
n
a
c
u
t
e
a
n
g
l
e
)
.
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Q.
If
s
e
c
(
4
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)
=
c
o
s
e
c
(
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, where
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Q.
Question 5
If
s
e
c
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=
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o
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(
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∘
)
, where 4A is an acute angle, find the value of A.
Q.
If sec 4A = cosec (A − 20°), where 4A is an acute angle, find the value of A.