It is 9.8 because to find the rise you'd need to find the angle between the hypotenuse and run which is cos (cosine which is run/hyp) on the calculator. Divide 2 by 10 and use cos-1 (reverse cosine) on the calculator to get the angle. After that, press the tangent button (tan which is rise/run or slope angle), and multiply it by the run, in this case, that would be 2 and you'd get 9.79 which rounded is 9.8