断点是否在圆内

 /// <summary>
        /// 判断点是否在圆内
        /// </summary>
        /// <param name="pointX">点的X坐标</param>
        /// <param name="pointY">点的Y坐标</param>
        /// <param name="circleCenterX">圆心X坐标</param>
        /// <param name="circleCenterY">圆心Y坐标</param>
        /// <param name="radius">圆的半径</param>
        /// <returns></returns>
        public static bool IsPointInCircle(float pointX, float pointY,
            float circleCenterX, float circleCenterY, float radius)
        {
            float x = pointX - circleCenterX;
            float y = pointY - circleCenterY;
            return Math.Sqrt(x * x + y * y) <= radius;
        }