LaTeX complains that \tkzDrawArc is not defined

Question

I'm trying to draw an arc between two points, centered at a third. I thought the following example should work

\documentclass{article}
\usepackage{tikz}
\usepackage{tkz-euclide}
\usetikzlibrary{calc}
\begin{document}

\begin{tikzpicture}[scale=1.5]
  \tkzDefPoint(0,0){O}
  \tkzDefPoint(2,-1){A}
  \tkzDefPoint(1,1){B}
  \tkzDrawArc[color=blue](O,A)(B)
  \tkzDrawArc[color=Maroon](O,B)(A)
  \tkzDrawArc(O,B)(A)
  \tkzDrawLines[add = 0 and .5](O,A O,B)
  \tkzDrawPoints(O,A,B)
  \tkzLabelPoints[below](O,A,B)
\end{tikzpicture}

\end{document}

instead I get an error message that \tkzDrawArc is an undefined control sequence.

Answer 1

You need to add the line

\usetkzobj{all}

to your preamble straight after \usepackage{tkz-euclide}. From the README in the CTAN entry for tkz-euclide:

To use the package tkz-euclide, place the following lines in the preamble of your LaTeX document.

\usepackage{tkz-euclide} 
\usetkzobj{all} 

\usepackage{tkz-euclide} loads tkz-base and TikZ. \usetkzobj{all} loads all objects used by tkz-euclide.

You’ll get a second error from the Maroon colour which isn’t defined yet; add the line

\usepackage[usenames, dvipsnames]{xcolor}

before you load tkz-euclide to get that colour.