Tangents

Purpose#

A tangent touches a circle or arc at exactly one point. LiberoDraft offers three tools for this, depending on what stands on the other side: a target line, a free point or a second circle. The result is always an ordinary line on the active layer.

For every starting situation several tangents are mathematically possible. Which one is drawn you determine with the click side: you click the circle where the tangent is meant to touch it.

Access#

• Ribbon: group Draw, triangle on the Line button — entries Tangent ⊥ (4), Tangent from point (5) and Tangent to 2 circles (6).
• Classic toolbar: drop-down triangle of the line family (1).
• Command search : Tangente.

Perpendicular tangent#

Perpendicular tangent Draws a tangent that ends at a right angle on a target line. The order is free: you may begin with the circle or with the line — the status bar first asks Click a circle/arc or a line and then for the remaining part (Click the target line — the tangent ends perpendicular on it or Click a circle or arc — the click side picks the tangent).

At the end the status bar reports Perpendicular tangent drawn. Two cases are refused: with an arc the touching point lies outside the drawn part (The tangent touches outside the arc — pick another arc or a circle), or the touching point falls onto the target line itself (Tangent point lies on the target line — no tangent possible).

Tangent from point#

Tangent from point Draws the tangent from a freely chosen point to a circle or arc. Two steps:

1. Click the start point (1) — Click the start point — the tangent starts there; object snap applies, so the point may lie on existing geometry.
2. Click the circle or arc (2) — Click a circle or arc — the click side picks the tangent. Of the two possible tangents the one on your click side is created.

At the end the status bar reports Tangent from point drawn. If the start point lies inside the circle there is no solution (The point lies inside the circle — no tangent possible); if it lies exactly on the circle the direction is not unique there (The point lies on the circle — tangent not determinable there).

Tangent to two circles#

Tangent to two circles Draws the common tangent to two circles or arcs. Two steps:

1. Click the first circle or arc (1) — Click the first circle or arc.
2. Click the second circle or arc (2) — Click the second circle or arc — the click sides pick the tangent.

The two click positions decide whether an outer or an inner (crossed) tangent is created. At the end the status bar reports Tangent to both drawn. If the same element is clicked twice, Please click a DIFFERENT circle or arc appears; if one circle lies entirely inside the other there is no common tangent (The circles are concentric — no common tangent). With arcs the touching points may lie on the missing parts of the full circles — the program then reports No tangent touches both on the arcs — pick other circles or arcs.

Options#

• The tangent is created on the active layer; pick up attribute (J) works as with all drawing tools.
• After drawing, the tool stays active and you can set the next tangent at once; Esc ends it.
• If Create dimension while drawing is on, the tangent receives its length dimension.

Related commands#

• Circle constructions — circle tangent to two or three elements
• Arcs tangent — arc with a radius between two elements
• Construction lines