Here we have collected some data from the graph of sin(x). We placed a point on the graph, drew a tangent to graph at that point and then measured the slope of the tangent. We then constructed a new point which plotted the x - coordinate of A vs. slope of the tangent. After collecting and plotting numerous data points in the spreadsheet function, we were able to conjecture that the derivative of sin(x) is cos(x). This was verified by drawing the graph of cos(x) - in red.