# What is the distance between the following polar coordinates?:  (1,(-5pi)/12), (8,(5pi)/8)

"Distance"=sqrt((r_1)^2+(r_2)^2-2r_1r_2cos(theta_2-theta_1)
D=sqrt(8^2+1^2-2*8*1cos((5pi)/8+(5pi)/12)
D=sqrt(65-16cos((25pi)/24)
$D \approx 8.9924$