if |A*B| =3A.B then the value of |A+B| is
A and B are vectors
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|AB| = 3A.B
|AB| = 3|A |.| B | cos∅ where ∅ is angle between a and b .
|AB| = 3|AB|cos∅
1 = 3cos∅
cos∅ = 1/3 -------(1)
| A + B | = √{A² + B² + 2|A|.|B|.cos∅}
= √{A² + B² + 2|A|.|B|.×1/3 }
when , A and B are unit vectors .
= √{ 1 + 1 + 2 × 1/3 }
= 2√2/3
|AB| = 3|A |.| B | cos∅ where ∅ is angle between a and b .
|AB| = 3|AB|cos∅
1 = 3cos∅
cos∅ = 1/3 -------(1)
| A + B | = √{A² + B² + 2|A|.|B|.cos∅}
= √{A² + B² + 2|A|.|B|.×1/3 }
when , A and B are unit vectors .
= √{ 1 + 1 + 2 × 1/3 }
= 2√2/3
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