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CBSE Class XII Maths 2018 Question Papers with Solutions
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Question : 1
Total: 29
Validate
Solution:
Given that the magnitude of each of the two vectors
→
a
and
→
b
have same magnitude.
⇒

→
a

=

→
b

... (i)
the angle between
→
a
and
→
b
is 60°
⇒ θ = 60°
and
→
a
.
→
b
=
3
2
... (iii)
Since,
→
a
.
→
b
=

→
a


→
b

cos θ
⇒

→
a


→
a

cos 60° =
9
2
From (i),(ii) and (iii)
⇒

→
a

2
×
1
2
=
9
2
⇒

→
a

2
= 9
⇒

→
a

= 3
⇒

→
a

=

→
b

= 3 ... From (i)
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