Question 1022514
You use the law of cosines to find the distance, where a and b are the radial distances and the angle in the formula is the difference between them...here a = 2, b = 3, and theta = 2π/3 - π/4 = 5π/12
So we can write
{{{c^2 = a^2 + b^2 - 2ab*cosC = 2^2 + 3^2 - 2(2)(3)cos(5pi/12)}}}
and
{{{c^2 = 13 - 12*cos(5pi/12)}}}
{{{c^2 = 9.894}}}
and 
c = 3.1455