Partial derivatives & Total Differential

Question 1 Not yet answered Marked out of1.O F Flag question a) lfz = xy xel'h' , show that .5 5 xi + y = xy + z. (4 marks] ( b) The surface area S of a right circular cone of radius r and height h is given by S = m3 + arr! where! is known as a slant height given as! = NH? + r2 . Suppose that the height increases from 12 cm to 12.5 cm and the diameter decreases from 18 cm to 17.2 cm. Estimate the change in the surface area of the right circular cone. (6 marks)