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Byju's Answer
Standard XII
Mathematics
In Radius
If r1,r2 and ...
Question
If
r
1
,
r
2
and
r
3
are
the
corresponding
exradii
of
a
Δ
ABC
and
r
is
the
inradii
of
the
same
triangle
,
then
−
1
r
1
+
1
r
2
+
1
r
3
=
1
r
A
True
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B
False
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Solution
The correct option is
A
True
We
know
that
,
r
1
=
Δ
s
−
a
,
r
2
=
Δ
s
−
b
r
3
=
Δ
s
−
c
,
r
=
Δ
s
1
r
1
+
1
r
2
+
1
r
3
=
1
Δ
s
−
a
+
1
Δ
s
−
b
+
1
Δ
s
−
c
=
s
−
a
+
s
−
b
+
s
−
c
Δ
=
3
s
−
(
a
+
b
+
c
)
Δ
=
(
3
s
−
2
s
Δ
)
=
s
Δ
=
1
r
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0
Similar questions
Q.
If
r
1
,
r
2
and
r
3
are
the
corresponding
exradii
of
a
Δ
ABC
and
r
is
the
inradii
of
the
same
triangle
,
then
−
1
r
1
+
1
r
2
+
1
r
3
=
1
r