r
i
j
k
⋅ + + =
r
9 Find the shortest distance between lines 
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
6
2
2
(
2
2
)
r
i
j
k
i
j
k
=
+
+
+ λ
−
+
r
and 
ˆ
ˆ
ˆ
ˆ
ˆ
4
(3
2
2
)
r
i
k
i
j
k
= −
−
+ µ
−
−
r 10 Find the coordinates of the point where the line through (5, 1, 6) and (3, 4,1)
crosses the YZ-plane