Tangent and secants to a circle from an external point
A point outside the circle sends a tangent and a fan of secants across it
From a point placed outside the circle, Leonardo draws a tangent together with a spreading fan of secant lines that cross the circle. The secants radiate from the external point and cut the circumference at successive points. The pencil figure studies how straight lines drawn from one outside point meet a circle.
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Tangent and pencil of secants from an external point
A circle is crossed by several straight lines that all issue from a single point lying outside it to the right, forming a fan of secants, with one line running as a tangent. The lines spread across the disc, meeting the circumference in pairs. The construction explores the relationship between an external point and the chords and tangent it determines.