Show that the points A(1, 2, 7), B(2, 6, 3) and C(3, 10, –1) are collinear 17 Show that the vectors 
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
2
,
3
5
and 3
4
4
i
j
k i
j
k
i
j
k
−
+
−
−
−
−
 form the vertices
of a right angled triangle 18