升高C点位置到K
//listPoint里是A C B 坐标
float x0 = listPoint[0].x();
float y0 = listPoint[0].y();
float x1 = listPoint[1].x();
float y1 = listPoint[1].y();
float x2 = listPoint[2].x();
float y2 = listPoint[2].y();
double distance;
distance = fabs(((y0 - y2) * x1 - (x0 - x2) * y1 + (x0 * y2 - x2 * y0)) / sqrt(pow(y0 - y2, 2) + pow(x0 - x2, 2)));
float ac = sqrt((x0 - x1) * (x0 - x1) + (y0 - y1) * (y0 - y1));
float ad=sqrt(ac * ac - distance * distance);
float tanAngleAB = (listPoint[2].y() - listPoint[0].y()) / (listPoint[2].x() - listPoint[0].x());
float angleAB = qAtan(tanAngleAB);
float ak = sqrt(ad * ad + 80 * 80);
float angleKAB = qAtan(80 / ad);
float angleAK = angleKAB + angleAB;
float x, y;
x = x0 + ak * cos(angleAK);
y = y0 + ak * sin(angleAK);
QPointF K(x, y);