what is tangent line?
Tangent Line. A straight line is tangent to a given curve at a point on the curve if the line passes through the point on the curve and has slope, where is the derivative of. This line is called a tangent line, or sometimes simply a tangent. SEE ALSO: Circle-Circle Tangents, Circle Tangent Line, Secant Line, Tangent, Tangent Plane, Tangent Space, Tangent Vector REFERENCES: