curves r=4(1+cost) and r=5(1-cost)

from sympy import *
r , t = symbols ('r,t')
r1=4*(cos ( t ) ) ;
r2=5*(sin ( t ) ) ;
dr1 = diff ( r1 , t )
dr2 = diff ( r2 , t )
t1=r1/dr1
t2=r2/dr2
q= solve ( r1-r2 , t )
23
w1=t1 . subs ({t: float ( q[0])})
w2=t2 . subs ({t: float ( q[0])})
y1= atan ( w1 )
y2= atan ( w2 )
w=abs( y1-y2 )
print ('Angle between curves in radians is %0.4f '% float ( w ) )