What font is this document?

Question

can anyone tell me the name of this font used in this document? thanks in advance. ?

Answer 1

This fragment should prove without any doubt that the document used

\usepackage[upright]{fourier}

Here's a sample code.

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}

\usepackage[upright]{fourier}

\usepackage{amsmath}

\begin{document}

Si $z_0\in\mathbb{C}$, on a succéssivement
\[
z_0\in\mathcal{H}(f)\Longleftrightarrow
\exists\theta\in[0,2\pi\mathclose{[}
\quad
\exists\varepsilon_1,\varepsilon_2\in\mathbb{U}
\qquad
z_0=\begin{bmatrix}
\overline{\varepsilon_1}\cos\theta\\
\overline{\varepsilon_2}\sin\theta
\end{bmatrix}
\cdot
\left(
  \begin{bmatrix}
  1 & 0 \\
  0 & 1
  \end{bmatrix}
  \begin{bmatrix}
  \varepsilon_1\cos\theta \\
  \varepsilon_2\sin\theta
  \end{bmatrix}
\right)
\]

\end{document}

Answer 2

There are several fonts in the image. An approximation:

\documentclass{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{upgreek}
\usepackage[sans]{dsfont}
\begin{document}
\textbf{1.3.}\quad Si $z_0 \in \mathds{C}$, on a successivement
\begin{gather*}
  \overline{\upepsilon_1} \cos\uptheta,
  \exists\uptheta \in [0; 2\uppi[\\
  \mathds{C}, \mathds{U}\\
  \mathcal{H}(f) \cdot \mathcal{L}_{\text{E}}\\
  \Longleftrightarrow \boxed{\left\{ 0 \leqslant \frac{1}{2}\right\}}
\end{gather*}
\end{document}

The set symbols by \mathds of package dsfont are close, but the result of \mathcal is quite different.