求解二次方程

W * cos(R) - H * sin(R) + x * cos(R) * 2 = a;

W * sin(R) + H * cos(R) + x * sin(R) * 2 = b;

-->

W * cos(R) * sin(R) - H * sin(R) * sin(R) + x * cos(R) * sin(R) * 2 = a  * sin(R);

W * sin(R) * cos(R) + H * cos(R) * cos(R) + x * sin(R) * cos(R) * 2 = b  * cos(R);

-->

W * cos(R) * sin(R) - H * sin(R) * sin(R) - W * sin(R) * cos(R) - H * cos(R) * cos(R) = a  * sin(R) - b  * cos(R)

-->

- H = a  * sin(R) - b  * cos(R)

-->

a  * sin(R) + H = b  * cos(R) 

let u = sin(R)

-->

(a*u+H)^2 = b^2*(1-u^2)

-->

a*a*u*u + H*H + 2*a*u*H = b*b - b*b*u*u

-->

(a*a+b*b)*u*u + 2*a*H*u + (H*H-b*b) = 0

let

A = (a*a+b*b)

B = 2*a*H

C = (H*H-b*b)

-->

u(0) = -B + sqrt(B*B-4*A*C)/2/A

u(1) = -B - sqrt(B*B-4*A*C)/2/A



R = asin(u[])

反带回去求取X，并验证虚解。