2. The Circle Post-Lab II A ( cm 2 ) r ( cm ) Area vs. Radius A ( cm 2 ) r 2 ( cm 2 ) Area vs. Radius 2 Since the graph is linear and contains (0,0) Y-intercept is negligible, meaning that when the radius is 0 cm, the area is 0 cm 2. Top opening parabola The area is proportional to the radius squared. Slopes

3. The Circle Post-Lab II A ( cm 2 ) r ( cm ) Area vs. Radius A ( cm 2 ) r 2 ( cm 2 ) Area vs. Radius 2 Since the graph is linear and contains (0,0) What is the slope or the constant of proportionality? General Math Model Constant of proportionality - the constant value of the ratio of two proportional quantities x and y ; usually written y = kx, where k is the constant of proportionality