What is the equation of the normal line to the curve y = x^2 + 2x -1 at point (1,2)
attempt: dy/dx = 2x + 0
dy/dx = 2x,
im stuck here
A normal line is perpendicular to the curve at the point of intersection, thus it is perpendicular to the tangent line at that point.
As far as the product of perpendicular slopes being -1, consider that the difference in their angles of inclination must be :
Using the identity we may write: