If 
and 
then value of 
is
Given that, 
Let θ be the angle between vector a and b.
Then, 
⇒ 12 = 10×2 cosθ
⇒ 
⇒ 
⇒ 
Now, 
⇒ 
28
If and then value of is
Given that,
Let θ be the angle between vector a and b.
Then,
⇒ 12 = 10×2 cosθ
⇒
⇒
⇒
Now,
⇒