Draw a tangent. Measure its gradient. Compare with differentiation.
Purple curve · pink tangent · teal rise and run
Drag P along the curve. Drag A and B along the tangent to choose two points for the gradient triangle.
Use x, parentheses, +, −, *, / and ^. Examples: 2*x^2+3*x, sin(x), cos(x), exp(x), ln(x), sqrt(x). Trig inputs are in radians.