i don’t know which one should i post on so i putted it into the general one so that it can be sorted

i need to make a shell, and there are some equations that i found for Fibonacci spiral, but is there a way to enter these equations?

i tried it with the maths function, but it says error for some reason

x(t) = a*e^{bt} *cos(t)
y(t) = a*e^{bt} *sin(t)

http://mathworld.wolfram.com/LogarithmicSpiral.html

please help me, or is there another way to make perfect shells?