Polar Tangents
#dy/dx = ((dr)/(d theta)sin(theta) + rcos(theta))/((dr)/(d theta)cos(theta) - rsin(theta) #
#r((-5pi)/3) = -(125pi^3)/27 + (5pi)/3 = (5pi)/3 - (125pi^3)/27#
Compute #(dr)/(d theta)# using wolframalpha
#(dr)/(d theta) = 3 θ^2-sin(θ+π/6)-θ cos(θ+π/6)#
Evaluate at #(-5pi)/3#
#(dr((-5pi)/3))/(d theta) = (25pi^2)/3 - 1#
#sin((-5pi)/3) = sqrt(3)/2#
#cos((-5pi)/3) = 1/2#
#dy/dx = ((dr)/(d theta)sqrt(3) + r)/((dr)/(d theta) - rsqrt(3) #
#dy/dx = ((25pi^2 - 3)sqrt(3) + 3r)/((25pi^2 - 3) - 3rsqrt(3) #
#dy/dx = ((25pi^2 - 3)sqrt(3) + 3((5pi)/3 - (125pi^3)/27))/((25pi^2 - 3) - 3((5pi)/3 - (125pi^3)/27)sqrt(3) #
The slope, #m ~~ 0.007#