equations
I have this equation in latex:
\{\Theta, \{\phi, \psi \}\} + \{\phi, \{\psi,\Theta \}\} + \{\psi, \{\Theta, \phi\}\} = 0
and codecogs.com/latex/eqneditor.php show me "Invalid Equation":
but stackedit.io/ is ok:
Because codecogs.com/latex/eqneditor.php doesn't work?
Do a \begin{align*} ... \end{align*}. That should do the trick.
I've done the following with your equation:
I've gotten rid of all \left and \right statements in favor of the following bracketing system: Innermost: square brackets, size default (small); next: round parentheses, size \big; outermost (just one instance): curly braces, size \big. The explicit sizing instructions are needed because the material enclosed in the \left ... \right pairs isn't big; hence the "fences" (brackets, parentheses, and braces) will all have the same minimum size unless explicit sizing instructions are provided.
Using the multline* environment of the amsmath package, I've broken up the expression into four lines, placing the < symbol at the start of the third line.
Replaced all \text{Sin} and \text{Cos} instances with \sin and \cos, respectively.
\documentclass{article}
\usepackage[margin=1.5in]{geometry} %choose margins for your document
\usepackage{amsmath}
\begin{document}
\begin{multline*}
\bigl(\text{xg} \cos[\alpha_2+\theta_1]
+(g+\text{yg}) \sin[\alpha_2+\theta_1]\bigr) m_2 R_2
+\bigl\{\cos[\alpha_c+\theta_1] \cos[\theta_1+\omega_c] d_c k_d\\
+\bigl(\text{xg} \cos[\alpha_c+\theta_1]
+(g+\text{yg}) \sin[\alpha_c+\theta_1]\bigr) m_d
-\cos[\alpha_c+\theta_1] \sin[\alpha_1] k_d R_1\bigr\} R_c\\
<\bigl(d \cos[\omega -\alpha_2] m_2 R_2
+\cos[\alpha_c-\omega_c] d_c m_d R_c\bigr)(\theta_1')^2\\
+\bigl(\text{IG2}+d \sin[\omega -\alpha_2] m_2 R_2
-\sin[\alpha_c-\omega_c] d_c m_d R_c\bigr) \theta_1''
\end{multline*}
\end{document}
Addendum: As @egreg has remarked in a comment, it's more common to use round parentheses as the innermost fences, square brackets for the mid-rank fences, and curly braces for the outermost fences. Switching the order of parentheses and brackets in the preceding examples produces the following look:
\documentclass{article}
\usepackage[margin=1.5in]{geometry} %choose margins for your document
\usepackage{amsmath
\begin{document}
\begin{multline*}
\bigl[\text{xg} \cos(\alpha_2+\theta_1)
+(g+\text{yg}) \sin(\alpha_2+\theta_1)\bigl] m_2 R_2
+\bigl\{\cos(\alpha_c+\theta_1) \cos(\theta_1+\omega_c) d_c k_d\\
+\bigl[\text{xg} \cos(\alpha_c+\theta_1)
+(g+\text{yg}) \sin(\alpha_c+\theta_1)\bigl] m_d
-\cos(\alpha_c+\theta_1) \sin(\alpha_1) k_d R_1\bigr\} R_c\\
<\bigl[d \cos(\omega -\alpha_2) m_2 R_2
+\cos(\alpha_c-\omega_c) d_c m_d R_c\bigl](\theta_1')^2\\
+\bigl[\text{IG2}+d \sin(\omega -\alpha_2) m_2 R_2
-\sin(\alpha_c-\omega_c) d_c m_d R_c\bigl] \theta_1''
\end{multline*}
\end{document}
Best Answer
I've tried to write with codecogs.com. I think the problem is that codecogs.com doesn't work very well. If you try with other equation you can obtain:
ERROR
I think if you use braces site works only with a small number of latex commands.