Math at McDonalds
The catenary (from latin "catena" meaning chain) is the curve a free hanging rope will take.
It can be described by the equation: y = a cosh(x/a) where cosh is the hyperbolic cosine function coshx=1/2 (e^x + e^-x).
After a challenge from Jacob Bernoulli to other mathematicians Huygens,Leibniz and Bernoullis brother Johann all independent discovered the formula in 1691.
The parabola is something different from the catenary - it`s equation are:
y = ax^2 + bx + c
In the software plot "a" is set to 1 in the catenary example, and "y = (x–1)^2 + 1" are used as an example of a parabolic curve.