On the inradius of a tangential quadrilateral - Martin Josefsson We give a survey of known formulas for the inradius r of a tangential quadrilateral, and derive the possibly new formula r = 2 Sqrt [(M-uvx)(M-vxy)(M-xyu)(M-yuv)/(uvxy(uv+xy)(ux+vy)(uy+vx))] ✪ ✪ ✪ ✪ ✪ Link tải tài liệu: LINK TẢI TÀI LIỆU Theo LTTK Education