A semicircular arched window has the curved shape modelled by the function w:[-4,4]- R, w(x)= Vr' -x' +c where r > 0 and CER* J(0). Let x be the horizontal distance in decimetres from the origin and let y be the vertical distance, in decimetres, from the x-axis. The shape of the window is shown below, where the coordinates of the y-intercept are (0, 5) and the coordinates of the extremes of the window are (-b,c) and (b, c). (0,5) (-b,c ) (b,c) >x a. State the radius of the semicircle. b. Hence find the rule for w