begin{subequations}
begin{align}
alpha_1 &=frac{1}{4}left[(L-1)^2 + tan ^2left(frac{2pi}{M}right)(L+1)^2right]\
alpha_2 &= 1 \
alpha_3 &=alpha_1\
alpha_4 &=alpha_1
end{align}
end{subequations}
The angle $theta$ values are
begin{subequations}
begin{align}
theta_1 &= tan^{-1} left[frac{L+1}{L-1}tanleft(frac{2pi}{M}right)right]\
theta_2 &= pi - theta_1\
theta_3 &=theta_1\
theta_4 &=frac{(M-2)pi}{M} - theta_1\[5pt]
end{align}
end{subequations}
and
begin{subequations}
begin{align}
phi_1 &= frac{pi}{2} - theta_1\
phi_2 &= frac{2pi}{M}\
phi_3 &= phi_1\
phi_4 &= frac{2pi}{M} + theta_1
end{align}
end{subequations}

documentclass[]{IEEEtran}

usepackage{amsmath}
usepackage{amssymb, amsfonts}
usepackage{changepage}


begin{document}


begin{subequations}
    begin{align}
    alpha_1 &=frac{1}{4}left[(L-1)^2 + tan ^2left(frac{2pi}{M}right)(L+1)^2right]\
    alpha_2 &= 1 \
    alpha_3 &=alpha_1\
    alpha_4 &=alpha_1
    end{align}
end{subequations}

The angle $theta$ values are
begin{adjustwidth}{-15.2mm}{0mm}
    begin{subequations}
        begin{align}
        theta_1 &= tan^{-1} left[frac{L+1}{L-1}tanleft(frac{2pi}{M}right)right]\
        theta_2 &= pi - theta_1\
        theta_3 &=theta_1\
        theta_4 &=frac{(M-2)pi}{M} - theta_1\[5pt]
        end{align}
    end{subequations}
end{adjustwidth}

and
begin{adjustwidth}{-42mm}{0mm}
    begin{subequations}
        begin{align}
        phi_1 &= frac{pi}{2} - theta_1\
        phi_2 &= frac{2pi}{M}\
        phi_3 &= phi_1\
        phi_4 &= frac{2pi}{M} + theta_1
        end{align}
    end{subequations}
end{adjustwidth}

end{document}