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Byju's Answer
Standard XII
Mathematics
Condition of Concurrency of 3 Straight Lines
Show that the...
Question
Show that the point
P
(
a
,
b
+
c
)
,
Q
(
b
,
c
+
a
)
and
R
(
c
,
a
+
b
)
are collinear.
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Solution
P
(
a
,
b
+
c
)
=
(
x
1
,
y
1
)
Q
=
(
b
,
c
+
a
)
=
(
x
1
,
y
2
)
R
=
(
c
,
a
+
b
)
=
(
x
3
,
y
3
)
m
p
q
=
s
l
o
p
e
o
f
P
Q
=
y
2
−
y
1
x
2
−
x
1
=
c
+
a
−
b
−
c
b
−
a
=
a
−
b
−
(
a
−
b
)
=
−
1
m
Q
R
=
s
l
o
p
e
o
f
Q
R
=
y
3
−
y
2
x
3
−
x
2
=
a
+
b
−
c
−
a
c
−
b
=
b
−
c
−
(
b
−
c
)
=
−
1
S
l
o
p
e
o
f
P
Q
=
S
l
o
p
e
o
f
Q
R
s
o
,
p
o
i
n
t
s
A
,
B
,
C
a
r
e
c
o
l
l
i
n
e
a
r
.
Suggest Corrections
0
Similar questions
Q.
Show that the following points are collinear:
(i) A(0, 1), B(1, 2) and C(−2, −1)
(ii) A(−5, 1), B(5, 5) and C(10, 7)
(iii) P(a, b + c), Q(b, c + a) and R(c, a + b)
Q.
In the given figure, PA, QB and RC are perpendicular to AC. If AP = x, QB = z, RC = y, AB = a and BC = b, show that
1
x
+
1
y
=
1
z
.