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Byju's Answer
Standard XII
Mathematics
Sum of Trigonometric Ratios in Terms of Their Product
In ABC, if ...
Question
In
△
A
B
C
, if
r
1
,
r
2
,
r
3
are in A.P., then
cot
(
A
/
2
)
,
cot
(
B
/
2
)
,
cot
(
C
/
2
)
are in
A
A.P.
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B
G.P.
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C
H.P.
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D
None of these
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Solution
The correct option is
D
H.P.
r
1
,
r
2
,
r
3
are in A.P.
⟹
s
tan
A
2
,
s
tan
B
2
,
s
tan
C
2
are in A.P.
∴
cot
A
2
,
cot
B
2
,
cot
C
2
are in H.P.
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Similar questions
Q.
Assertion :In a
△
A
B
C
, if
a
<
b
<
c
and
r
is inradius and
r
1
,
r
2
,
r
3
are the axradii opposite to angle
A
,
B
,
C
respectively, then
r
<
r
1
<
r
2
<
r
3
Reason:
△
A
B
C
,
r
1
r
2
+
r
2
r
3
+
r
3
r
1
=
r
1
r
2
r
3
r
Q.
In
Δ
A
B
C
the sides opposite to angles
A
,
B
,
C
are denoted by
a
,
b
,
c
respectively.
r
is the in-radius of the traingle
A
B
C
If
r
1
,
r
2
,
r
3
are in A.P. for the triangle
A
B
C
, then
cot
(
A
/
2
)
,
cot
(
B
/
2
)
,
cot
(
B
/
2
)
are in?
Q.
If in a triangle ABC , (a - b) (s - c) = (b - c) (s - a), prove that
r
1
,
r
2
,
r
3
are in A.P
Q.
If
a
,
c
,
d
are in A.P., then
r
1
,
r
2
,
r
3
are in
Q.
Statement
−
1
: In a
Δ
A
B
C
, if
a
<
b
<
c
and
r
is in-radius and
r
1
,
r
2
,
r
3
are the exradii opposite to angle
A
,
B
,
C
respectively, then
r
<
r
1
<
r
2
<
r
3
.
Statement
−
2
: For,
Δ
A
B
C
r
1
r
2
+
r
2
r
3
+
r
3
r
1
=
r
1
r
2
r
3
r
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