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Byju's Answer
Standard X
Mathematics
Trigonometric Ratios of Standard Angles
Question 9 If...
Question
Question 9
If
s
i
n
A
+
s
i
n
2
A
=
1
, then the value of
(
c
o
s
2
A
+
c
o
s
4
A
)
is
(A)
1
(B)
1
2
(C)
2
(D)
3
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Solution
The answer is (A).
Given,
s
i
n
A
+
s
i
n
2
A
=
1
⇒
s
i
n
A
=
1
−
s
i
n
2
A
=
c
o
s
2
A
[
∵
s
i
n
θ
+
c
o
s
2
θ
=
1
]
O
n
s
q
u
a
r
i
n
g
b
o
t
h
s
i
d
e
s
w
e
g
e
t
,
s
i
n
2
A
=
c
o
s
4
A
⇒
1
−
c
o
s
2
A
=
c
o
s
4
A
⇒
c
o
s
2
A
+
c
o
s
4
A
=
1
(
A
n
s
.
)
.
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Similar questions
Q.
Question 9
If
s
i
n
A
+
s
i
n
2
A
=
1
, then the value of
(
c
o
s
2
A
+
c
o
s
4
A
)
is
(A)
1
(B)
1
2
(C)
2
(D)
3
Q.
If
sin
A
+
sin
2
A
=
1
Then,
(
cos
2
A
+
cos
4
A
)
=
?
Q.
If
sin
A
+
sin
2
A
=
1
, then the value of the expression
(
cos
2
A
+
cos
4
A
)
is
Q.
If
sin
A
+
sin
2
A
=
1
, then show that
cos
2
A
+
cos
4
A
=
1
.
Q.
If sin A + sin
2
A = 1, then the value of cos
2
A + cos
4
A is
(a) 2
(b) 1
(c) −2
(d) 0