1.
Vectors a\vec{a} and b\vec{b} make an angle θ=2π3\theta = \dfrac{2\pi}{3}. If a=1|\vec{a}| = 1, b=2|\vec{b}| = 2 then {(a+3b)×(3ab)}2=\{(\vec{a} + 3\vec{b}) \times (3\vec{a} - \vec{b})\}^2 =