#r=thetacos((7pi)/4-3theta)#
#color(blue)(d/(d(theta)))r=color(blue)(d/(d(theta)))(thetacos((7pi)/4-3theta)#
#(dr)/(d(theta))=cos((7pi)/4-3theta)+3thetasin((7pi)/4-3theta)#
#cos((7pi)/4-3((-2pi)/3))+3((-2pi)/3)sin((7pi)/4-3((-2pi)/3))#
#cos((7pi)/4+2pi)-2pisin((7pi)/4+2pi)#
#cos((7pi)/4)-2pisin((7pi)/4)#
#sqrt2/2-2pi*-sqrt2/2#
#((1+2pi)sqrt2)/2#