Creating a tangent line from a point is similar to creating a regular line. Just start creating a line and move it close enough to become a tangent to the given circle. The line snaps to the tangent line automatically.
You can also build a tangent line through a point on a circle. You need to activate the Tangent tool and then tap a point on a circle. You can build tangent lines for ellipses, parabolas and hyperbolas the same way.
← How do I create a tangent line?