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Let the angle θ, 0 < θ < 2 π between two unit vectors a ˆ and b ˆ be sin –1 . 9 65 ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ If the vector c = 3 a ˆ +6 b ˆ + 9( a ˆ × b ˆ ), then the value of 9 ) b ˆ . c

1. a ˆ . c ( − is
2. 24
3. 27
4. 31 (4) 29

Correct answer: 31 (4) 29

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