You can either use the intersection library to calculate the intersection of the path (C)-(c) with another path at height 8/9C (the red path in the first picture).
\path[draw,red, name path=target] ($...
One way is not to draw two paths, but one path at two thicknesses
\coordinate (O) at (0,0);
With the TikZ library math looks quite intuitive :)
%Two points (A) and (B)
\coordinate (A) at (0,...
With some styles and declare function for constants. The grids are drawn manually with one loop, the ticks with labels with a second loop. Use the scale parameter to adjust the size of the diagram.
A solution using TikZ powerful let...in syntax, which produces a code short and readable:
You're almost there. Two things to fix:
\cos is a macro defined to typeset cos. To have PGF parse it as the cosine function you have to remove the backslash and let it parse the three letters c, o, s ...
You can use polar coordinates such as (55:100cm). In the code below, I compute the precise number of oblique lines to draw in function of the chosen angle \myAngle and the distance \myDist between two ...
You can make use of the fit-library. You can pass the nodes you want to include to the fit-option and put the fitting-node on the background layer.
In your example it is sufficient to fit the three ...
You could do something like this:
Here is another method to extract coordinate values from a node or an anchor. Its advantage is to provide these values taking account of the current origin.
Have a look at the following code:
\draw[blue] (0,0) circle (1);
\node[circle, fill=orange, label=above left :$...
Not as pgf-hacky as the other answers, but how about the following.
Very straight forward, simple and easy to understand workaround.