(1 + 1 + 1 – 6) + λ (2 + 3 + 4 + 5) = 0
or
λ = 3
14
Putting the values of  λ in (1), we get
3
9
6 ˆ
ˆ
ˆ
1
1
1
7
14
7
r
i
j
k








+
+
+
+
+
















r
 = 
15
6 14
−
or
10
23
13 ˆ
ˆ
ˆ
7
14
7
r
i
j
k


+
+




r
 = 69
14
or
ˆ
ˆ
ˆ
(20
23
26 )
r
i
j
k
⋅
+
+
r
 = 69
which is the required vector equation of the plane 11 7  Coplanarity of Two Lines
Let the given lines be
rr  = 
1
1
a
b
+λ
r
r (1)
and
rr  = 
2
2
a
b
+ µ
r
r