CHAPTER 31
Hence,
31.12
about the y-axis.
We used the fact that
254
31.8
about the AC-axis.
Then
about the y-axis.
31.9
Use
So
Then
about the *-axis.
31.10 y
2 = l2x, 0 31.11 y* + 4x = 2\ny, 0 We have
Thus,
Now,
So
In
In
In
about the y-axis.
31.13
Now,
Thus,
Let x =
By Problem 28.40, this is equal
In
So we arrive at
In
In
In
In
In
In
31.14
Find the surface area of a right circular cone of height h and radius of base r.
As is shown in Fig. 31-1, the cone is obtained by revolving about the *-axis the region in the first quadrant
Hence,
under the line
tan 0, dx = sec
2 0 dO. Then
1 Now, 2vy' = 12, 4y
2 (y')
2 = 144,
y = lnjc, l to