Xrfgtjtk

How to make a bigger space between equation and its number? Thank you.

begin{document}

begin{equation}label{apsidalni}

omega_c = frac{360}{P} left[k_{2,1} (15qf(e) + (1+q)g(e,1))r_1^5+k_{2,2}left(frac{15}{q}f(e)+left(1+frac{1}{q}right)g(e,2)right)r_2^5 right]

end{equation}

end{document}

Here are a few suggestions. You can move down the equation number by adding an invisible object, here rule[-36pt]{0pt}{36pt} ({0pt}{0pt} means zero width and height, but the optional value -36pt tells TeX to move down the invisible rule by the stated amount); of course 36pt is exaggerated, use a smaller value.

On the other hand, splitting the equation seems better, so I add a couple of ways for it.

documentclass[a4paper]{article}

usepackage[left=4cm,right=4cm]{geometry}

usepackage{amsmath}



usepackage[nopar]{lipsum} % for context



numberwithin{equation}{section}



begin{document}



setcounter{section}{3}setcounter{equation}{21}



lipsum[4][1-5]

begin{equation}label{apsidalni}

omega_c = frac{360}{P} left[k_{2,1} (15qf(e)

  + (1+q)g(e,1))r_1^5+k_{2,2}left(frac{15}{q}f(e)

  +left(1+frac{1}{q}right)g(e,2)right)r_2^5 right]

end{equation}

lipsum[4][1-5]

begin{equation}label{apsidalni-lowered}

omega_c = frac{360}{P} left[k_{2,1} (15qf(e)

  + (1+q)g(e,1))r_1^5+k_{2,2}left(frac{15}{q}f(e)

  +left(1+frac{1}{q}right)g(e,2)right)r_2^5 right]

rule[-36pt]{0pt}{0pt}

end{equation}

lipsum[4][1-5]

begin{multline}label{apsidalni-multline}

omega_c = frac{360}{P} biggl[k_{2,1} (15qf(e)

  + (1+q)g(e,1))r_1^5

\

  +k_{2,2}left(frac{15}{q}f(e)

  +left(1+frac{1}{q}right)g(e,2)right)r_2^5 biggr]

end{multline}

lipsum[4][1-5]

begingroup

addtolength{multlinegap}{4em}

begin{multline}label{apsidalni-multline-gap}

omega_c = frac{360}{P} biggl[k_{2,1} (15qf(e)

  + (1+q)g(e,1))r_1^5

\

  +k_{2,2}left(frac{15}{q}f(e)

  +left(1+frac{1}{q}right)g(e,2)right)r_2^5 biggr]

end{multline}

endgroup

lipsum[4][1-5]



end{document}

Here I guessed the text width based on your image.

Here are three ways: either you split the equation on two lines (with multline or with a nested aligned), or you use the medmath command, from nccmath, which makes its argument about 80 % of displaysize.

Also, if you don't use margin notes, you can have more decent margins just loading the geometry package.

documentclass{article}

usepackage{mathtools, nccmath}

usepackage{showframe}

renewcommand{ShowFrameLinethickness}{0.3pt}



begin{document}



begin{multline}label{apsidalni}

omega_c = frac{360}{P} biggl[k_{2,1} (15qf(e) + (1+q)g(e,1))r_1^5 \

+k_{2,2}left(frac{15}{q}f(e)+left(1+frac{1}{q}right)g(e,2)right)r_2^5 biggr]

end{multline}

bigskip

begin{equation}label{apsidalni-1}

begin{aligned}

omega_c = frac{360}{P} biggl[k_{2,1} (15qf(e) & + (1+q)g(e,1))r_1^5 \

& + k_{2,2}left(frac{15}{q}f(e)+left(1+frac{1}{q}right)g(e,2)right)r_2^5 biggr]

end{aligned}

end{equation}

bigskip



begin{equation}label{apsidalni-2}

omega_c = medmath{frac{360}{P} biggl[k_{2,1} (15qf(e) + (1+q)g(e,1))r_1^5 \

+k_{2,2}left(frac{15}{q}f(e)+left(1+frac{1}{q}right)g(e,2)right)r_2^5 biggr]}

end{equation}



end{document}