Calculus- Early Transcendentals, 2021a

560 Vector Calculus
Exercise 16.6.7 Find the area of the portion of x 2 + y 2 + z 2 = a 2 that lies above x 2 + y 2 ≤ b 2 .
Exercise 16.6.8 Find the area of z = x 2 − y 2 that lies inside x 2 + y 2 = a 2 .
Exercise 16.6.9 Find the area of x 2 + y 2 + z 2 = a 2 that lies above the interior of the circle given in polar
coordinates by r = acosθ.
Exercise 16.6.10 Find the area of the cone z = k √ x 2 + y 2 that lies above the interior of the circle given
in polar coordinates by r = acosθ.
Exercise 16.6.11 Find the area of the plane z = ax + by + c that lies over a region D with area A.
Exercise 16.6.12 Find the area of the cone z = k √ x 2 + y 2 that lies over a region D with area A.
Exercise 16.6.13 Find the area of the cylinder x 2 + z 2 = a 2 that lies inside the cylinder x 2 + y 2 = a 2 .
Exercise 16.6.14 The surface f (x,y) can be represented with the vector function 〈x,y, f (x,y)〉. Setupthe
surface area integral using this vector function and compare to the integral of Section 14.4.
16.7 Surface Integrals
In the integral for surface area, from Equation 16.7,
∫ b ∫ d
a
c
|r u × r v |dudv,
the integrand |r u × r v |dudv is the area of a tiny parallelogram, that is, a very small surface area, so it is
reasonable to abbreviate it dS; then a shortened version of the integral is
∫∫
1 · dS.
We have already seen that if D is a region in the plane, the area of D may be computed with
∫∫
1 · dA,
so this is really quite familiar, but the dS hides a little more detail than does dA.
Just as we can integrate functions f (x,y) over regions in the plane, using
∫∫
D
D
D
f (x,y)dA,
so we can compute integrals over surfaces in space, using
∫∫
f (x,y,z)dS.
D