The second book of the "Conics" where the properties of the asymptotic lines of hyperbolas are examined, while the examination of the properties of the tangents and the conjugate diameters of the conic sections continues. In the third book, the following are examined: a) the relationships of the triangles and quadrilaterals formed by the intersection of the tangents of the conic sections with the diameters drawn from the points of contact; b) the rectangles formed by the segments of the chords intersecting each other within the conic sections; c) the harmonic division of the lines intersecting within the conic sections; d) the focus of the hyperbola and the ellipse.