Matlab三角函数求解

求解这四个函数用matlab能解出三个角度吗，li=0.502941,mi=-0.3,ni=0.810586
我的代码如下：
clear;
clc;
% syms li mi ni a b c
syms li mi ni alpha beta gamma;
li = 0.502941;
mi = -0.3;
ni = 0.810586;
ni*(cos(alpha)/2 - (3^(1/2)cos(beta)sin(alpha))/2) - mi(sin(gamma)((3^(1/2)*cos(alpha))/2 + (cos(beta)*sin(alpha))/2) + cos(gamma)sin(alpha)sin(beta)) - li(cos(gamma)((3^(1/2)*cos(alpha))/2 + (cos(beta)*sin(alpha))/2) - sin(alpha)*sin(beta)*sin(gamma))==1/2;

li*(cos(gamma)*((3^(1/2)*sin(alpha))/2 - (cos(alpha)*cos(beta))/2) + cos(alpha)sin(beta)sin(gamma)) + mi(sin(gamma)((3^(1/2)*sin(alpha))/2 - (cos(alpha)*cos(beta))/2) - cos(alpha)*cos(gamma)sin(beta)) - ni(sin(alpha)/2 + (3^(1/2)*cos(alpha)*cos(beta))/2)==-sqrt(3)/2;

li*(cos(beta)*sin(gamma) + (cos(gamma)sin(beta))/2) + mi((sin(beta)*sin(gamma))/2 - cos(beta)*cos(gamma)) + (3^(1/2)nisin(beta))/2==0;

tan(beta)==-2*tan(gamma);
这个求解该用什么函数解啊
老是报错，不知道该用什么函数求解了 能不能有朋友帮我看看，第四个方程是为了限制gamma 和beta的关系的 但是还是返回无解

solve，fmincon都可以试一下