Graphical Demonstration of the Derivative of Sine x
Use this applet to investigate and convince yourself the graphical approach to finding the derivative of the function y = sin x
Use the slider to move point P along the y = sin x function and note the gradient of the tangent at that point.
A plot of the gradient of the tangent vs the x coordinate of P ie which forms coordinates of new point Q, (by tracing Q as P moves)
will reveal that the derivate of sin x is actually cos x.
Check this for yourself