Sally Is on a Day Hike at Mt

Essay

Sally is on a day hike at Mt.Baker.From 9 to 11:00 a.m.she zig-zags up z = f(x, y)where x is the number of miles due east of her starting position, y is the number of miles due north of her starting position, and z is her elevation in miles above sea level.Feeling tired, she decides to continue walking, but in such a way that her altitude remains constant from 11 a.m.to noon to settle her stomach for lunch.At 11:30 a.m., she will be passing through (2, -1, 5)where f_x(2, -1)= 3 and f_y(2, -1)= -2.
What is the slope of her "path" in the x, y plane at this instant? (This "path" is among the level curves in the plane.)