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 MATHEMATI CS
494
12 Find the angle between the planes whose vector equations are
ˆ
ˆ
ˆ
(2
2
3 )
5
r
i
j
k
⋅
+
−
=
r
and  
ˆ
ˆ
ˆ
(3
3
5 )
3
r
i
j
k
⋅
−
+
=
r 13 In the following cases, determine whether the given planes are parallel or
perpendicular, and in case they are neither, find the angles between them