a = (25/2) = 12.5

b = (10/2) = 5

e = sqrt(1-(b^2/a^2)) = sqrt(1-(25/156.25)) = sqrt(0.16) = 0.4

r(t) = (12.5*5)/sqrt((12.5sin(t))^2+(5cos(t))^2)

t r x y
0 12.5 12.5 0
pi/12 10.751586084406789 10.385234672498676 2.782715243703712
2pi/12 8.219949365267865 7.118684968143744 4.109974682633932
3pi/12 6.56532164298613 4.642383454426301 4.642383454426296
4pi/12 5.625439504630121 2.812719752315062 4.871773518462232
5pi/12 5.146902837677898 1.3321164776832513 4.971526376313572
pi/2 5 0 5
7pi/12 5.146902837677896 -1.3321164776832455 4.971526376313572
8pi/12 5.625439504630117 -2.8127197523150556 4.871773518462232
9pi/12 6.565321642986127 -4.642383454426296 4.642383454426296
10pi/12 8.21994936526786 -7.118684968143738 4.109974682633933
11pi/12 10.751586084406778 -10.385234672498663 2.78271524370372
pi 12.5 -12.5 0