Tangents Tool

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

• Selecting a point A and a conic c produces all tangents through A to c.
• Selecting a line g and a conic c produces all tangents to c that are parallel to line g.
• Selecting a point A and a function f produces the tangent line to f in x = x(A).
• Selecting two circles c and d produces the common tangents to the two circles (up to 4).

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

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