The following code instructs TikZ to draw an obtuse triangle. Except for the placement of the letter "C" in the diagram, the diagram is drawn correctly. I want to move the letter "C" downwards a little more so that it is not on the triangle.
\documentclass[10pt]{amsart}
\usepackage{tikz}
\usetikzlibrary{calc,angles,positioning,intersections,quotes,decorations.markings}
\usepackage{tkz-euclide}
\usetkzobj{all}
\begin{document}
\begin{tikzpicture}
\path (110:4.5) coordinate (A) (-30:3) coordinate (B) (0:0) coordinate (C);
\draw (A)
-- (B) node [at start, above left]{$A$} node [midway, right]{$c$}
-- (C) node [at start, right]{$B$} node [midway, below] {$a$}
-- (A) node [at start, below, left]{$C$} node [midway, left] {$b$} -- cycle;
\coordinate (P) at ($(B)!(A)!(C)$);
\draw[dashed] (A) -- (P) node [below, left]{$P$} node [midway, left]{$h$} -- (C);
\draw[dashed] (P) -- node [midway, below]{$x$}(C);
\draw[|<->|] ($(B)!7mm!90:(P)$)--node[fill=white,sloped] {$a + x$} ($(P)!7mm!-90:(B)$);
\draw pic[draw, angle radius=2mm,"$\theta$",angle eccentricity=2] {angle = B--C--A};
\tkzMarkRightAngle(A,P,C);
\end{tikzpicture}
\end{document}



left belowandbelow below leftare not defined and hence are not possible. – Aug 31 '14 at 23:27