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Byju's Answer
Standard X
Mathematics
Heights and Distances
Question 8If ...
Question
Question 8
If
Δ
A
B
C
is right angled at C, then the value of cos(A+B) is
(A) 0
(B) 1
(C)
1
2
(D)
√
3
2
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Solution
The answer is (A).
We know that, in
Δ
A
B
C
, sum of three angles
=
180
∘
i.e.,
∠
A
+
∠
B
+
∠
C
=
180
∘
But right angled at C i..e,
∠
C
=
90
∘
[given]
∠
A
+
∠
B
+
∠
C
=
180
∘
⇒
A
+
B
=
90
∘
∴
c
o
s
(
A
+
B
)
=
c
o
s
90
∘
⌊
∵
∠
A
=
A
⌋
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Similar questions
Q.
Question 8
If
Δ
A
B
C
is right angled at C, then the value of cos(A+B) is
(A) 0
(B) 1
(C)
1
2
(D)
√
3
2
Q.
In ∆ ABC, right angled at B, if tan A =
1
/
√3
then the value of sin A + cos A is