If a=1, b=2 and the angle between a and b is 1200, then a+3b×3a-b2=..............

a+3b×3a-b2=3a×a-a×b+9b×a-3b×b2=10b×a2=102b2a2sin2a, b=1002212sin21200=4003/22=300.

If a=1, b=2 and the angle between a and b is 1200, then a+3b×3a-b2=..............

a+3b×3a-b2=3a×a-a×b+9b×a-3b×b2=10b×a2=102b2a2sin2a, b=1002212sin21200=4003/22=300.

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If $|a| = 1, |b| = 2$ and the angle between a and b is $120^{0},$ then ${\{(a + 3 b) \times (3 a - b)\}}^{2} = . . . . . . . . . . . . . .$

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${\{(a + 3 b) \times (3 a - b)\}}^{2} = {\{3 a \times a - a \times b + 9 b \times a - 3 b \times b\}}^{2}$

$= {\{10 (b \times a)\}}^{2} = 10^{2} {|b|}^{2} {|a|}^{2} \sin^{2} (a, b) = 100 {(2)}^{2} {(1)}^{2} \sin^{2} (120^{0}) = 400 {(\sqrt{3} / 2)}^{2}$ $= 300$ .

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If a=1, b=2 and the angle between a and b is 1200, then a+3b×3a-b2=..............

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If $|a| = 1, |b| = 2$ and the angle between a and b is $120^{0},$ then ${\{(a + 3 b) \times (3 a - b)\}}^{2} = . . . . . . . . . . . . . .$