Parametric Equations

The Foci of an Ellipse

This worksheet illustrates the relationship between an ellipse and its foci. Move the yellow point along the ellipse.
What are the red points called?
What is the relationship between each of the green (resp. blue) line segments?
What happens to the [i]sum [/i]of the lengths of the green and blue line segments as the yellow point moves along the ellipse?

Sum/Difference of Vectors

This worksheet gives a geometric interpretation of the sum and difference of two vectors. (The yellow points may be moved.)
How do the dashed vectors compare to the solid vectors?
What is the significance of the green vector?
What is the significance of the black vector?

Level Curves

This worksheet illustrates the level curves of a function of two variables. You may enter any function which is a polynomial in both [math]x[/math] and [math]y[/math].

Partial Derivatives and Slope

This worksheet illustrates the connection between partial derivatives and slope. Move the yellow point (in the xy-plane) and compare the value of the partial derivative to the slope of the black line.

Gradient vs. Level Curves

Move the yellow point to see how the gradient of the function (whose graph is the red surface) changes. Note that (1) the gradient is always perpendicular to the level curves, (2) though the gradient points in the direction of greatest change, this direction is not always directly toward the "summit" (i.e. the local maximum), and (3) the magnitude (length) of the gradient is equal to the slope of the tangent line to the surface in the direction of the gradient (this is the solid black line on the right side).

Small Cylindrical Volumes

Adjust the values of [math]r[/math], [math]\theta[/math], [math]z[/math], [math]\Delta r[/math], [math]\Delta\theta[/math], and [math]\Delta z[/math] to see how the small cylindrical volume changes. Note that this volume has approximate dimensions [math]\Delta r \times (r\Delta\theta) \times \Delta z= r\Delta r\Delta\theta\Delta z[/math].
Small Cylindrical Volumes

Vector Field in the Plane

This worksheet illustrates a (scaled) vector field in the [math]xy[/math]-plane. Specify the vector field by defining the component functions [math]P(x,y)[/math] and [math]Q(x,y)[/math] and scaling constant [math]k[/math]. Move the position of the black point to observe the "value" of the vector field at that point.
Vector Field in the Plane

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