Back to Active Calculus Multivariable

Parameterizations of Surfaces and Surface Area

Describing a curved surface with two parameters, and computing its area by integrating the magnitude of a cross product of partial derivative vectors.

Active Calculus Multivariable, Parameterizations of Surfaces and Surface Area

Status
FlagsLoading your progress…

5 exercises

Activity 13.10.4

Let z=f(x,y)z = f(x,y) define a smooth surface, and consider the parameterization r⃗(s,t)=⟨s,t,f(s,t)⟩\vr(s,t) = \langle s, t, f(s,t) \rangle.

  1. Let DD be a region in the domain of ff. Using equation, show that the area of the surface defined by the graph of ff over DD is .

  2. Use the formula developed in the previous part to calculate the area of the surface defined by f(x,y)=4−x2f(x,y) = \sqrt{4-x^2} over the rectangle D=[−2,2]×[0,3]D = [-2,2] \times [0,3].

  3. Observe that the surface of the solid describe the previous part is half of a circular cyl…

2.5

Exercise 23

Consider the ellipsoid given by the equation

In Activity, we found that a parameterization of the sphere SS of radius RR centered at the origin is for −π2≤s≤π2-\frac{\pi}{2} \leq s \leq \frac{\pi}{2} and 0≤t≤2π0 \leq t \leq 2\pi.

  1. Let (x,y,z)(x,y,z) be a point on the ellipsoid and let X=x4X = \frac{x}{4}, Y=y5Y = \frac{y}{5}, and Z=z3Z = \frac{z}{3}. Show that (X,Y,Z)(X,Y,Z) lies on the sphere SS. Hence, find a parameterization of SS in terms of XX, YY, and ZZ as functions of ss and tt.

  2. Use the result of part (a) to find a parameterization of the ellipse…

2.5

Exercise 24

2.5

Exercise 25

Consider the plane generated by z=f(x,y)=24−2x−3yz = f(x,y) = 24 - 2x - 3y over the region D=[0,2]×[0,3]D = [0,2]\times[0,3].

  1. Sketch a picture of the overall solid generated by the plane over the given domain.

  2. Determine a parameterization r⃗(s,t)\vr(s,t) for the plane over the domain DD.

  3. Use Equation to determine the surface area generated by ff over the domain DD.

  4. Observe that the vector u⃗=⟨2,0,−4⟩\vu = \langle 2, 0, -4 \rangle points from (0,0,24)(0,0,24) to (2,0,20)(2,0,20) along one side of the surface generated by the plane ff over DD. Find the vector v⃗\vv…

2.5

Exercise 26

2.5

Adapted from Active Calculus Multivariable © 2013–2026 Nicholas Long, Mitchel T. Keller, and Steven Schlicker. Licensed under CC BY-SA 4.0. Source: Active Calculus Multivariable. Imported at revision 692c03c.