<Table> <Tr> <Th> conic section </Th> <Th> equation </Th> <Th> eccentricity (e) </Th> <Th> linear eccentricity (c) </Th> <Th> semi-latus rectum (l) </Th> <Th> focal parameter (p) </Th> </Tr> <Tr> <Td> circle </Td> <Td> x 2 + y 2 = a 2 (\ displaystyle x ^ (2) + y ^ (2) = a ^ (2) \,) </Td> <Td> 0 (\ displaystyle 0 \,) </Td> <Td> 0 (\ displaystyle 0 \,) </Td> <Td> a (\ displaystyle a \,) </Td> <Td> ∞ (\ displaystyle \ infty) </Td> </Tr> <Tr> <Td> ellipse </Td> <Td> x 2 a 2 + y 2 b 2 = 1 (\ displaystyle (\ frac (x ^ (2)) (a ^ (2))) + (\ frac (y ^ (2)) (b ^ (2))) = 1) </Td> <Td> 1 − b 2 a 2 (\ displaystyle (\ sqrt (1 - (\ frac (b ^ (2)) (a ^ (2)))))) </Td> <Td> a 2 − b 2 (\ displaystyle (\ sqrt (a ^ (2) - b ^ (2)))) </Td> <Td> b 2 a (\ displaystyle (\ frac (b ^ (2)) (a))) </Td> <Td> b 2 a 2 − b 2 (\ displaystyle (\ frac (b ^ (2)) (\ sqrt (a ^ (2) - b ^ (2))))) </Td> </Tr> <Tr> <Td> parabola </Td> <Td> y 2 = 4 a x (\ displaystyle y ^ (2) = 4ax \,) </Td> <Td> 1 (\ displaystyle 1 \,) </Td> <Td> N / A </Td> <Td> 2 a (\ displaystyle 2a \,) </Td> <Td> 2 a (\ displaystyle 2a \,) </Td> </Tr> <Tr> <Td> hyperbola </Td> <Td> x 2 a 2 − y 2 b 2 = 1 (\ displaystyle (\ frac (x ^ (2)) (a ^ (2))) - (\ frac (y ^ (2)) (b ^ (2))) = 1) </Td> <Td> 1 + b 2 a 2 (\ displaystyle (\ sqrt (1 + (\ frac (b ^ (2)) (a ^ (2)))))) </Td> <Td> a 2 + b 2 (\ displaystyle (\ sqrt (a ^ (2) + b ^ (2)))) </Td> <Td> b 2 a (\ displaystyle (\ frac (b ^ (2)) (a))) </Td> <Td> b 2 a 2 + b 2 (\ displaystyle (\ frac (b ^ (2)) (\ sqrt (a ^ (2) + b ^ (2))))) </Td> </Tr> </Table> <Tr> <Th> conic section </Th> <Th> equation </Th> <Th> eccentricity (e) </Th> <Th> linear eccentricity (c) </Th> <Th> semi-latus rectum (l) </Th> <Th> focal parameter (p) </Th> </Tr> <Tr> <Td> circle </Td> <Td> x 2 + y 2 = a 2 (\ displaystyle x ^ (2) + y ^ (2) = a ^ (2) \,) </Td> <Td> 0 (\ displaystyle 0 \,) </Td> <Td> 0 (\ displaystyle 0 \,) </Td> <Td> a (\ displaystyle a \,) </Td> <Td> ∞ (\ displaystyle \ infty) </Td> </Tr> <Tr> <Td> ellipse </Td> <Td> x 2 a 2 + y 2 b 2 = 1 (\ displaystyle (\ frac (x ^ (2)) (a ^ (2))) + (\ frac (y ^ (2)) (b ^ (2))) = 1) </Td> <Td> 1 − b 2 a 2 (\ displaystyle (\ sqrt (1 - (\ frac (b ^ (2)) (a ^ (2)))))) </Td> <Td> a 2 − b 2 (\ displaystyle (\ sqrt (a ^ (2) - b ^ (2)))) </Td> <Td> b 2 a (\ displaystyle (\ frac (b ^ (2)) (a))) </Td> <Td> b 2 a 2 − b 2 (\ displaystyle (\ frac (b ^ (2)) (\ sqrt (a ^ (2) - b ^ (2))))) </Td> </Tr>

Consider the diagram lines e and c can be described as