title: Left align a block of equations inside a proof using LaTeX
body: <p>I am suffering with this LaTeX document. <strong>I am trying to left align the block of equations inside a proof.</strong> There is a famous question about this on stack overflow:</p>
  
  <p><a href="https://stackoverflow.com/questions/2632628/left-align-block-of-equations">Left align block of equations</a></p>
  
  <p>However, I tried using <code>\documentclass[fleqn]{article}</code>. It didn't work. I also tried using  <code>\begin{flalign}</code>, it didn't work.</p>
  
  <p><strong>The math in my text looks ugly. I wish it was centralized or left aligned.</strong></p>
  
  <p>That's how it looks:
  <a href="https://i.stack.imgur.com/oaTl8.png" rel="nofollow noreferrer">appearance of the text</a></p>
  
  <p>This is the code:</p>
  
  <pre><code>\documentclass[fleqn]{article}
  \usepackage[utf8x]{inputenc} 
  \usepackage[T1]{fontenc}
  \usepackage{textcomp}
  \usepackage{gensymb}
  \usepackage{titling}
  \usepackage{lipsum}
  \usepackage{url}
  \usepackage{graphicx}
  \usepackage{color}
  \usepackage[usenames,dvipsnames,svgnames,table]{xcolor}
  \usepackage{amsmath}
  \usepackage{amsmath}
  \usepackage{amsthm}
  \usepackage{amssymb}
  \graphicspath{{images/}}
  
  
  \begin{document}
  
  \newpage
  
  
  \begin{proof}
    \begin{align*}
      \text{Seja: } \gamma(t) = (r \cos t,r\sin t, a\sin t + b\cos t +c)  \\
      \text{Primeira derivada: }\gamma'(t) = (-r\sin t,r\cos t,   a\cos t - b\sin t)  \\
      \text{Segunda derivada: }\gamma''(t) = (-r\cos t,-r\sin t,    -a\sin t - b\cos t)  \\
      \text{Terceira derivada: }\gamma'''(t) = (r\sin t,-r\cos t, -a\cos t + b\sin t)  \\
      \text{A torção pode ser expressa por: }\tau  = {{\left(   {r' \times r''} \right) \cdot r'''} \over {\left\| {r' \times r''} \right\|^2}}\\
      \text{A fórmula acima não exige que a curva esteja      parametrizada pelo cumprimento   de arco} \\
      \text{Desenvolvendo os cálculos do numerador}  \\
      \text{O produto vetorial das duas primeiras derivadas é:  } {\gamma'(t) \times \gamma''(t)= (-rb, -  ra, r²)}\\
      \text{O produto escalar é o produto vetorial vezes a   terceira derivada: } \\
      (-rb, -ra, r²)\cdot \gamma'''(t)  \\
      (-rb, -ra, r²)\cdot (r\sin t,-r\cos t, -a\cos t + b\sin t)   = 0 \\
      \text{O numerador é zero. Logo, a torção é zero. } \\
      \tau = 0 \\
      \text{Se a torção é zero, a curva é plana.} 
    \end{align*}
  \end{proof}
  </code></pre>