设P为凸多边形A1A2A3…An的一个内点,且满足∠PA1A2=∠PA2A3=…=∠PAnA1=θ,则点P称为多边形A1A2A3…An的B rocard点,角θ称为这多边形的B rocard角.关于多边形B rocard点的性质,文[1]通过迂回曲折的论证,得到了如下命题:定理1设P是双圆四边形ABCD的勃罗卡点,∠PAB=∠PBC=∠PCD Let P be an inward point of the convex polygon A1A2A3...An and satisfy ∠PA1A2=∠PA2A3=...=∠PAnA1=θ, then the point P is called the Brocard point of the polygon A1A2A3...An, and the angle θ is called the B of this polygon. Rocard angle. On the nature of polygonal B rocard points, the paper [1] obtained the following proposition through the twists and turns of the argument: Theorem 1 Let P be the Broca point of the double circular quadrilateral ABCD, and ∠PAB=∠PBC=∠PCD.