Can someone me with this math problem

To find the extreme values of a function f(x.y) on a curve x-x(t), y y(t), treat f as a function of the single variable t and use the chain rule to find where df/dt is zero. in any other single-variable case, the extreme values of f are then found among the values at the critical points (points where df/dt is zero or fails to exist), and endpoints of the parameter domain. find the absolute maximum and minimum values of the following function on the given curves. use the parametric equations x=2cos t, y 2 sin t functions: curves: i) the semicircle x4,y20 i) the quarter circle x2+y-4, x20, y20 b, g(x,y)=xy

Me d is also an option but i couldn't get it in the picture

The distribution of a sample of the outside diameters of pvc pipes approximates a symmetrical, bell-shaped distribution. the arithmetic mean is 14.0 inches, and the standard deviation is 0.1 inches. about 68% of the outside diameters lie between what two amounts?