I need to combine an involute (https://en.wikipedia.org/wiki/Involute) of a circle and an archimedean spiral in one TikZ drawing, but have a problem drawing the involute.
I need something like this:
Here is my code:
\usepackage{tikz}
\usepackage{pgfplots}
\pgfplotsset{compat=1.11}
\usepackage{fp}
\usetikzlibrary{fixedpointarithmetic}
\begin{tikzpicture}[x=1mm, y=1mm]
\draw[] (0, 0) circle (7mm);
\draw[rotate=-90, blue, domain=0:2*pi, variable=\a, samples=500]
plot[fixed point arithmetic] ({\a r}:{7*sqrt(1+pow(\a, 2))});
\draw[rotate=-90, red, domain=0:2*pi, variable=\a, samples=500]
plot[fixed point arithmetic] ({\a r}:{(7*\a)});
\end{tikzpicture}
And the output is:
Found my error, here is the code for involute and the circle:
\def\r{7}
% Circle
\draw[line width=0.1mm, domain=0:2*pi, variable=\t, samples=500]
plot[fixed point arithmetic] ({\r*cos(deg(\t))}, {\r*sin(deg(\t))});
% Involute
\draw[blue, line width=0.1mm, domain=0:2*pi, variable=\t, samples=500]
plot[fixed point arithmetic] ({\r*(cos(deg(\t))+\t*sin(deg(\t)))}, {\r*(sin(deg(\t))-\t*cos(deg(\t)))});
% Spiral
\draw[red, rotate=-90, line width=0.1mm, domain=0:2*pi, variable=\t, samples=500]
plot[fixed point arithmetic] ({\t r}:{(7*\t)});
And the fixed output is: