Find the equation of the plane through the line of intersection of the
planes x + y + z = 1 and 2x + 3y + 4z = 5 which is perpendicular to the plane
x – y + z = 0 © NCERT
not to be republished
 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