y1 = int(Re*(L1+Re*t*tan(K))*sin(b1_1-t),t,0,b1_1)-...
        int(Re*(L1+Re*t*tan(K))*sin(t-b1_1),t,b1_1,A)- ...
        int(Re*a *sin(t-b1_1),t,A,B)-...
        int(Re*(a-Re*(t-B)* tan(K)) *sin(t-b1_1),t,B,pi);
    b1_1 = solve(y1==0,b1_1);

错误使用 solve (line 265)
Specify a variable for which you solve.

出错 zsh11_hudu (line 32)
    b1_1 = solve(y1==0,b1_1);