Tangent planes in space

### 27.5.3 Tangent planes in space

See Section 26.6.7 for tangents in the plane.

The tangent command finds tangent planes to surfaces.

- tangent takes two arguments:
  - obj, an object in space.
  - P, a point in space.

    If obj is the graph of a function, then P can be a point in the domain of the function, and the point on the graph will be used.

  or
  - e, a point defined with element (see Section 26.5.15) using a curve and parameter value.
- tangent(objP) returns and draws the plane through P that’s perpendicular to obj.

#### Examples

S:=sphere([0,0,0],3); tangent(S,[2,2,1])

G:=plotfunc(x^2+y^2,[x,y]); tangent(G,[2,2])