The area of the circle is the function of its radius, A = pi r^2 (i) Draw two circles, one with radius r and second with radius r + delta r, where delta r is reasonably small. (ii) State delta A and dA symbolically. (iii) Shade area representing delta A on the sketch. (iv) Describe why dA is a good approximation to delta A 2. Peeling the orange changes its volume V. What delta V represents? (i) Volume of rind (ii) surface area of orange (iii) volume of edible part of orange.