The tangent to the graph of at is extended one unit to the right to form a right-angled triangle whose hypotenuse has the slope . Therefore the tangent function of the angle of at is and can be read off the scale to the right of . Read the first two digits from the brown scale and the third digit from the pink Vernier scale, where a pink mark is aligned with a brown mark.
Wolfram Demonstrations Project
Published: February 28 2013