Question

If â and 6 are non-collinear unit vectors and
if lâ+61=13, then the value of
(28 - 56)-(3â+6) is :-​

Answer 1

Answer:1/2

Explanation:Note that if v is any vector then v^2 = v^2 that is a vector square equals its modulus square because

v^2. = v. v = v v Cos 0 = v^2 and if u is a unit vector then | u | = 1.

For two non- collinear unit vectors a and b say inclined at an angle of t degree, it is given that,

| a+b | = sqrt (3) implies | a +b |^2 = 3 or ( a +b ). (a +b ) = 3 ==> a.a + a.b + b.a + b.b = 3 or

a^2 + 2 ( a .b ) + b^2 = 3 or 1 + 2 ( a .b ) + 1 = 3 ==> ( a .b ) = 1/2 or Cost = 1/2 or t = 60 degree.

Now;

( a - b ). ( 2 a +b ) = 2 ( a. a ) + ( a .b ) - 2 ( b.a ) - b.b = 2 a^2 - ( a. b ) - b^2 = 2 - (1/2) - 1 = 1/2 .

Answer 2

Answer:

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