I’ve done a line in a coordinate system but I want to know the tangent of point. How can I get the tangent?
Edit your question (don’t answer it) to explain “I’ve done a line” by giving the formula you wrote. How’s a “tangent of a point” related to the line?
Is your question related to the math formula editor in LibO? Is it a numeric application in Calc? Is your question about mathematics? If yes, this Q&A site is dedicated only to LibO usage issues, not to classroom assignments.
The tangent to a point on a straight line is the same line. Perhaps you are looking, instead, for a line that is perpendicular to the line at that point? Unless the “line” you have constructed is a curve …
As @ajlittoz requests, what is the formula for the “line” you have constructed??