#### Answer

$$ 2\sqrt7$$

#### Work Step by Step

Firstly we will have to convert polar points to Cartesian
$(2, \pi/3)$
Thus, $x = rcosθ = 2\times cos(\pi/3) = 2\times \frac{1}{2} = 1$
$y = rsinθ = 2\times sin(\pi/3) = 2\times \frac{\sqrt 3}{2}= \sqrt 3$
Therefore we have First point $(x_1,y_1)=(1, \sqrt 3)$
$x = rcosθ = 4\times cos(2\pi/3) = 4\times \frac{-1}{2} = -2$
$y = rsinθ = 4\times sin(2\pi/3) = 4\times \sqrt 3/2 = 2\sqrt 3$
Thus, $(x_2,y_2)=(-1, 2\sqrt 3)$
Distance Formula, D = $\sqrt{ (x_2-x_1)^{2} + (y_2-y_1)^{2}}$
$ =\sqrt {(-1-1)^{2} + (2\sqrt3-\sqrt3)^{2}}$
Hence, $$D=2 \sqrt 7$$