User:Pyro05x/Sandbox

$$r = \frac{ab}{\sqrt{a^2 \sin^2 \theta + b^2 \cos^2 \theta}}=\frac{b}{\sqrt{1-\varepsilon^2 \cos^2 \theta}}$$

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)