If the radius r of a spreading circular rash is increasing at a rate of 0.7 cm/day, then the area A = *r2 of the rash increases at a rate of ... cm /day when the radius of the rash is 3 cm. Note: r is a function of t (time) a) 2.8n Ob) 4.27 O c) 5.67 O d) 7n Oe) None of the above