Tangents Tool

Tangents to a conic section can be produced in several ways (see also Tangent command):

  • Selecting a point and a conic produces all tangents through the point to the conic.

  • Selecting a line and a conic produces all tangents to the conic that are parallel to the selected line.

  • Selecting a point and a function produces the tangent line to the function in its point having the same x-coordinate of the selected point (e.g. if the point is A, the tangent is drawn in x = x(A)).

  • Selecting two circles produces the common tangents to them (up to 4).

Type \( y = x^2+2x+1 \) rather than \( f(x) = x^2 + 2x + 1 \) if you want a conic (parabola) rather than a function.

x(A) represents the x-coordinate of point A. If point A lies on the function graph, the tangent runs through point A.