Grab the blue point at the tail of the arrow move it around; move the dot at the head of the arrow to change which direction we're taking the directional derivative in.[br][br]The red line is the line whose slope computes [math]\frac{\partial f}{\partial x}[/math]; the green line is the line whose slope computes [math]\frac{\partial f}{\partial y}[/math]. [br]The black line is the line whose slope computes [math]D_Vf\left(A\right)[/math].[br][br]Use the toggle switches to change visibility:[br][br]graphvisible turns the graph of f on and off.[br]xtangentvisible turns the tangent line whose slope is [math]\frac{\partial f}{\partial x}[/math] on and off.[br]ytangentvisible turns the tangent line whose slope is [math]\frac{\partial f}{\partial y}[/math] on and off.[br]planevisible turns the tangent plane on and off.[br][br]Vslicevisible turns the slice which we use to compute [math]D_Vf\left(A\right)[/math] on and off.[br][br]normalvisible turns the normal [math]n=\left\langle1,0,f_x\left(A\right)\right\rangle\times\left\langle0,1,f_y\left(A\right)\right\rangle[/math] on and off.[br][br]Enter your own function in place of the default [math]f\left(x,y\right)=sin\left(x\right)-y^3[/math].