(a) Let

→

a

=

^

i

+

^

j

,

→

b

=

^

i

−

^

j

and

→

c

=

^

i

+

^

j

+

^

k

. If

^

n

is a unit vector such that

→

a

⋅

^

n

=0 and

→

b

.

^

n

=0, then find ∣

→

c

⋅

^

n

|

OR
(b) If

→

a

and

→

b

are unit vectors inclined at an angle 30∘ to each other, then find the area of the parallelogram with (

→

a

+3

→

b

) and (3

→

a

+

→

b

) as adjacent sides.