Lab 7 Directional Derivative Calculus 3, Dr Samuels please write your answers on this sheet and turn it in what does this grapher do? This tool illustrates the directional derivative of a function f(x,y) at a point (an) in the direction of a vector v. Each graph does the same thing for a different function. You can vary the point (ah) with the sliders. or click the 1+' then type in a new value then press enter. The direction vector in the xy-plane is graphed in red with unit length. The half-plane which projects to it is graphed in gray. and the intersection of that plane and the surface is a line graphed in blue. The directional derivative vector is graphed in purple. You can change the direction vector v (and the intersecting plane) by manipulating the angle t, 0