For the first tangen point, use the SmartDrag function. Click the circle close to the point, the tangent should start and keep the left button down while you move the mouse in tangent direction. A small circle will appear, when the program has detected the tangency. Than you can release the button an draw the line, which will be tangent to the first circle. Click the second point at the tangent snap position of the second circle (as you described). By the way:

• its also possible to drag the first point normal to the cirle. and
• to draw an arc, tangent to three curves, use SmartDrag at the first and second point/curve and click the third at the tangent snap position of the third curve.